MIT-OCW-Transcripts / -B96m5X2xCM.txt
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for all our applications and for the lab
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for all our applications and for the lab
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for all our applications and for the lab
sessions I guess they keep using Albert
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sessions I guess they keep using Albert
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sessions I guess they keep using Albert
Einstein this is the 100th anniversary
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Einstein this is the 100th anniversary
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Einstein this is the 100th anniversary
of is the famous year 1905 so just a
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of is the famous year 1905 so just a
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of is the famous year 1905 so just a
little celebration one slide of a
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little celebration one slide of a
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little celebration one slide of a
reminder of what we have seen in the
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reminder of what we have seen in the
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reminder of what we have seen in the
previous previous lecture we had really
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previous previous lecture we had really
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previous previous lecture we had really
developed the formalism and leading to
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developed the formalism and leading to
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developed the formalism and leading to
the hartree-fock equations and the
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the hartree-fock equations and the
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the hartree-fock equations and the
hartree-fock equation follow from a
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hartree-fock equation follow from a
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hartree-fock equation follow from a
certif you know very simple and very
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certif you know very simple and very
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certif you know very simple and very
beautiful path we have the Schrodinger
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beautiful path we have the Schrodinger
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beautiful path we have the Schrodinger
equation and we have reformulated the
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equation and we have reformulated the
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equation and we have reformulated the
Schrodinger equation in terms of the
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Schrodinger equation in terms of the
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Schrodinger equation in terms of the
variational principle so we have a
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variational principle so we have a
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variational principle so we have a
functional and we know that we can throw
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functional and we know that we can throw
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functional and we know that we can throw
into that functional any arbitrary wave
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into that functional any arbitrary wave
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into that functional any arbitrary wave
function and they'll give us an
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function and they'll give us an
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function and they'll give us an
expectation value of the energy and set
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expectation value of the energy and set
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expectation value of the energy and set
of the closer we get to the true ground
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of the closer we get to the true ground
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of the closer we get to the true ground
state wave function the lower the
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state wave function the lower the
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state wave function the lower the
Tenergy is going to be we are not we are
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Tenergy is going to be we are not we are
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Tenergy is going to be we are not we are
never going to go below the ground state
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never going to go below the ground state
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never going to go below the ground state
energy instead sort of a very powerful
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energy instead sort of a very powerful
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energy instead sort of a very powerful
approach to try out a sort of
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approach to try out a sort of
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approach to try out a sort of
possibilities and solution and in
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possibilities and solution and in
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possibilities and solution and in
particular set of Hartree and Foca took
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particular set of Hartree and Foca took
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particular set of Hartree and Foca took
this approach they wrote a set of the
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this approach they wrote a set of the
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this approach they wrote a set of the
most general many-body wave function
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most general many-body wave function
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most general many-body wave function
that can be written as a product of
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that can be written as a product of
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that can be written as a product of
single particle orbitals that was
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single particle orbitals that was
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single particle orbitals that was
actually the original heart resolution
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actually the original heart resolution
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actually the original heart resolution
we functions written as data do not
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we functions written as data do not
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we functions written as data do not
satisfy a fundamental symmetry of
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satisfy a fundamental symmetry of
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satisfy a fundamental symmetry of
interacting fermions that is they are
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interacting fermions that is they are
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interacting fermions that is they are
not antisymmetric and so what you do you
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not antisymmetric and so what you do you
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not antisymmetric and so what you do you
take this product of single particle
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take this product of single particle
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take this product of single particle
orbitals and you sum it with all the
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orbitals and you sum it with all the
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orbitals and you sum it with all the
possible permutation with all the
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possible permutation with all the
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possible permutation with all the
possible signs in front of so that the
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possible signs in front of so that the
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possible signs in front of so that the
overall wave function is anti-symmetric
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overall wave function is anti-symmetric
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overall wave function is anti-symmetric
and that can be sort of written
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and that can be sort of written
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and that can be sort of written
compactly as what is called a Slater
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compactly as what is called a Slater
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compactly as what is called a Slater
determinant here and basically now our
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determinant here and basically now our
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determinant here and basically now our
unknowns
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unknowns
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unknowns
are the N
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are the N
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are the N
orbitals Phi and so we need to determine
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orbitals Phi and so we need to determine
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orbitals Phi and so we need to determine
the shape of this n single particle
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the shape of this n single particle
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the shape of this n single particle
orbitals and we want to determine them
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orbitals and we want to determine them
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orbitals and we want to determine them
such that they minimize the expectation
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such that they minimize the expectation
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such that they minimize the expectation
value of the variational principle and
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value of the variational principle and
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value of the variational principle and
so that leads basically to a set of
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so that leads basically to a set of
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so that leads basically to a set of
differential equation is just functional
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differential equation is just functional
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differential equation is just functional
analysis and when you ask yourself what
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analysis and when you ask yourself what
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analysis and when you ask yourself what
are the condition that those single
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are the condition that those single
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are the condition that those single
particle orbitals need to satisfy in
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particle orbitals need to satisfy in
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particle orbitals need to satisfy in
order to minimize the variational
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order to minimize the variational
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order to minimize the variational
principle well this is it the
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principle well this is it the
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principle well this is it the
hartree-fock equation so each a single
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hartree-fock equation so each a single
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hartree-fock equation so each a single
particle orbital Phi of lambda need to
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particle orbital Phi of lambda need to
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particle orbital Phi of lambda need to
satisfy basically a shredding ER like a
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satisfy basically a shredding ER like a
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satisfy basically a shredding ER like a
question again as always there is a
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question again as always there is a
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question again as always there is a
kinetic energy term here there is the
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kinetic energy term here there is the
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kinetic energy term here there is the
interaction with the external potential
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interaction with the external potential
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interaction with the external potential
that is just the potential of the nuclei
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that is just the potential of the nuclei
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that is just the potential of the nuclei
and then come the so-called mean field
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and then come the so-called mean field
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and then come the so-called mean field
terms so the electron lambda here will
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terms so the electron lambda here will
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terms so the electron lambda here will
interact with each and every other
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interact with each and every other
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interact with each and every other
electron move via an electrostatic
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electron move via an electrostatic
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electron move via an electrostatic
interaction you see Phi star times Phi
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interaction you see Phi star times Phi
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interaction you see Phi star times Phi
is the charge density coming from the
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is the charge density coming from the
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is the charge density coming from the
orbital mu and they feel that they're
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orbital mu and they feel that they're
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orbital mu and they feel that they're
the electron lambda feels is the
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the electron lambda feels is the
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the electron lambda feels is the
electrostatic average density and in
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electrostatic average density and in
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electrostatic average density and in
this app with sum over all the electrons
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this app with sum over all the electrons
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this app with sum over all the electrons
including the electron lambda so up to
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including the electron lambda so up to
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including the electron lambda so up to
now we have a system that is self
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now we have a system that is self
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now we have a system that is self
interacting an electron lambda feels the
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interacting an electron lambda feels the
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interacting an electron lambda feels the
electrostatic interaction with itself
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electrostatic interaction with itself
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electrostatic interaction with itself
that in principle is not correct but
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that in principle is not correct but
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that in principle is not correct but
luckily this next term that is called
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luckily this next term that is called
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luckily this next term that is called
the exchange term cancels that exactly
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the exchange term cancels that exactly
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the exchange term cancels that exactly
and the exchange term is that direct
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and the exchange term is that direct
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and the exchange term is that direct
consequence of having written the trial
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consequence of having written the trial
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consequence of having written the trial
wavefunction not just as a product of
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wavefunction not just as a product of
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wavefunction not just as a product of
single particle orbital because up to
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single particle orbital because up to
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single particle orbital because up to
now we would have sort of something
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now we would have sort of something
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now we would have sort of something
closer to the heart equation but written
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closer to the heart equation but written
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closer to the heart equation but written
as a proper antisymmetric wave function
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as a proper antisymmetric wave function
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as a proper antisymmetric wave function
summing on all the permutation with them
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summing on all the permutation with them
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summing on all the permutation with them
appropriate science' and so basically we
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appropriate science' and so basically we
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appropriate science' and so basically we
are treating it like a question a great
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are treating it like a question a great
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are treating it like a question a great
advantage with respect to the harsh
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advantage with respect to the harsh
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advantage with respect to the harsh
equation is now the operator doesn't
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equation is now the operator doesn't
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equation is now the operator doesn't
change depending on the index lambda
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change depending on the index lambda
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change depending on the index lambda
because this sense if you want to go
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because this sense if you want to go
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because this sense if you want to go
over all the electrons including lambda
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over all the electrons including lambda
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over all the electrons including lambda
so our only constraint here is that we
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so our only constraint here is that we
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so our only constraint here is that we
need to find the N lowest eigenstate of
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need to find the N lowest eigenstate of
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need to find the N lowest eigenstate of
this single differential equation so if
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this single differential equation so if
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this single differential equation so if
we have n electrons if you want it's not
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we have n electrons if you want it's not
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we have n electrons if you want it's not
that we have n different
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that we have n different
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that we have n different
differential equation like it was the
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differential equation like it was the
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differential equation like it was the
case of the Hart equation but we have a
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case of the Hart equation but we have a
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case of the Hart equation but we have a
identical differential equation that is
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identical differential equation that is
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identical differential equation that is
written here and we need to find that
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written here and we need to find that
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written here and we need to find that
the N lowest energy states and those
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the N lowest energy states and those
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the N lowest energy states and those
will be our single particle or because
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will be our single particle or because
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will be our single particle or because
in all of these that we have started
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in all of these that we have started
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in all of these that we have started
from a variational principle so it's
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from a variational principle so it's
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from a variational principle so it's
very easy to go beyond the hartree-fock
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very easy to go beyond the hartree-fock
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very easy to go beyond the hartree-fock
we can say enlarge our variational
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we can say enlarge our variational
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we can say enlarge our variational
classes we can add more Slater
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classes we can add more Slater
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classes we can add more Slater
determinant with sort of different
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determinant with sort of different
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determinant with sort of different
coefficients we can try to construct a
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coefficients we can try to construct a
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coefficients we can try to construct a
more complex wave function and that
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more complex wave function and that
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more complex wave function and that
solution will become better and better
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solution will become better and better
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solution will become better and better
or we can sort of use a perturbation
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or we can sort of use a perturbation
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or we can sort of use a perturbation
theory and so quantum chemistry has
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theory and so quantum chemistry has
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theory and so quantum chemistry has
developed a number of techniques that
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developed a number of techniques that
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developed a number of techniques that
are post r34 techniques that become
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are post r34 techniques that become
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are post r34 techniques that become
systematically more and more accurate
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systematically more and more accurate
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systematically more and more accurate
they are also more and more expensive
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they are also more and more expensive
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they are also more and more expensive
and that's if you want the main
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and that's if you want the main
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and that's if you want the main
limitation of that direction
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limitation of that direction
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limitation of that direction
what we see today is something as they
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what we see today is something as they
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what we see today is something as they
say Monty Python completely different
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say Monty Python completely different
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say Monty Python completely different
and that will be set of density
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and that will be set of density
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and that will be set of density
functional theory that if you want a
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functional theory that if you want a
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functional theory that if you want a
theory that starts from a very different
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theory that starts from a very different
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theory that starts from a very different
set of hypothesis the net result will be
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set of hypothesis the net result will be
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set of hypothesis the net result will be
again a set of single particle equations
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again a set of single particle equations
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again a set of single particle equations
the terrset are very similar actually
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the terrset are very similar actually
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the terrset are very similar actually
formally to the hartree-fock equation
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formally to the hartree-fock equation
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formally to the hartree-fock equation
but they have been derived in a
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but they have been derived in a
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but they have been derived in a
completely different spirit density
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completely different spirit density
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completely different spirit density
function theory tends to be less
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function theory tends to be less
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function theory tends to be less
expensive than hartree-fock and overall
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expensive than hartree-fock and overall
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expensive than hartree-fock and overall
tends to be more accurate especially for
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tends to be more accurate especially for
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tends to be more accurate especially for
solid is much more accurate or you'll
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solid is much more accurate or you'll
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solid is much more accurate or you'll
see when we discuss case studies the
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see when we discuss case studies the
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see when we discuss case studies the
hartree-fock solution for the say
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hartree-fock solution for the say
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hartree-fock solution for the say
interacting electron gas or in general
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interacting electron gas or in general
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interacting electron gas or in general
for metals tends to make them
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for metals tends to make them
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for metals tends to make them
semiconducting or insulating like so
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semiconducting or insulating like so
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semiconducting or insulating like so
hard she folk tend towards very poorly
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hard she folk tend towards very poorly
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hard she folk tend towards very poorly
for solids and that's why if you want
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for solids and that's why if you want
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for solids and that's why if you want
density functional theory comes from the
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density functional theory comes from the
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density functional theory comes from the
solid state community while hartree-fock
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solid state community while hartree-fock
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solid state community while hartree-fock
that tends to work very well for atoms
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that tends to work very well for atoms
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that tends to work very well for atoms
comes from the quantum chemistry
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comes from the quantum chemistry
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comes from the quantum chemistry
community and all the theory was
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community and all the theory was
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community and all the theory was
developed by world corner and coworkers
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developed by world corner and coworkers
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developed by world corner and coworkers
you see the Homburg and con theorem the
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you see the Homburg and con theorem the
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you see the Homburg and con theorem the
connection mapping during the six days
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connection mapping during the six days
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connection mapping during the six days
but I would say it's only during the 70s
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but I would say it's only during the 70s
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but I would say it's only during the 70s
that people started to be able to
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that people started to be able to
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that people started to be able to
actually solve interesting cases using
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actually solve interesting cases using
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actually solve interesting cases using
density functional theory and it's
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density functional theory and it's
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density functional theory and it's
really the beginning of the 80s you'll
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really the beginning of the 80s you'll
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really the beginning of the 80s you'll
see some cases here today in which
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see some cases here today in which
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see some cases here today in which
people started calculating something
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people started calculating something
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people started calculating something
that had sort of a direct application so
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that had sort of a direct application so
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that had sort of a direct application so
we will see the phase diagram of silicon
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we will see the phase diagram of silicon
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we will see the phase diagram of silicon
as a function of pressure or volume and
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as a function of pressure or volume and
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as a function of pressure or volume and
sort of the first first principle
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sort of the first first principle
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sort of the first first principle
prediction of properties of solids
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prediction of properties of solids
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prediction of properties of solids
Walther corner for the development of
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Walther corner for the development of
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Walther corner for the development of
the intervention theory got the Nobel
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the intervention theory got the Nobel
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the intervention theory got the Nobel
Prize for chemistry in 1998 together
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Prize for chemistry in 1998 together
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Prize for chemistry in 1998 together
with John popper that has been the
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with John popper that has been the
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with John popper that has been the
person that has been sort of
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person that has been sort of
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person that has been sort of
most that's been fundamental in the
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most that's been fundamental in the
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most that's been fundamental in the
development of hartree-fock and poor
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development of hartree-fock and poor
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development of hartree-fock and poor
posture terrific approaches in quantum
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posture terrific approaches in quantum
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posture terrific approaches in quantum
chemistry okay so let's see sort of what
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chemistry okay so let's see sort of what
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chemistry okay so let's see sort of what
is that the general idea behind the ends
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is that the general idea behind the ends
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is that the general idea behind the ends
differential theory and in many ways
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differential theory and in many ways
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differential theory and in many ways
will sort of start from idea that had
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will sort of start from idea that had
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will sort of start from idea that had
been developed at the end of the 20s or
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been developed at the end of the 20s or
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been developed at the end of the 20s or
at the beginning of the 30s what is
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at the beginning of the 30s what is
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at the beginning of the 30s what is
nowadays calls the thomas fiering
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nowadays calls the thomas fiering
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nowadays calls the thomas fiering
approach and again the basic idea here
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approach and again the basic idea here
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approach and again the basic idea here
is that the wave function of a many body
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is that the wave function of a many body
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is that the wave function of a many body
interacting problem is an object that is
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interacting problem is an object that is
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interacting problem is an object that is
too complex to treta and it would be
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too complex to treta and it would be
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too complex to treta and it would be
very very nice if we could instead try
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very very nice if we could instead try
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very very nice if we could instead try
to deal with a simple object and sort of
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to deal with a simple object and sort of
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to deal with a simple object and sort of
one of the choices could be the charge
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one of the choices could be the charge
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one of the choices could be the charge
density so if you want a thomas and firm
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density so if you want a thomas and firm
align:start position:0%
density so if you want a thomas and firm
independently we're asking themselves
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independently we're asking themselves
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independently we're asking themselves
well could we try to solve not really as
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well could we try to solve not really as
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well could we try to solve not really as
trading an equation in the many-body
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trading an equation in the many-body
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trading an equation in the many-body
wave function but solve something else
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wave function but solve something else
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wave function but solve something else
in which our only unknown is the charge
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in which our only unknown is the charge
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in which our only unknown is the charge
density if you think for a moment the
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density if you think for a moment the
align:start position:0%
density if you think for a moment the
charge density is one of the sort of
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charge density is one of the sort of
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charge density is one of the sort of
fundamental variables in the description
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fundamental variables in the description
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fundamental variables in the description
of an interacting electron problem and
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of an interacting electron problem and
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of an interacting electron problem and
so this is this was the question can we
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so this is this was the question can we
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so this is this was the question can we
do something just with the charge
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do something just with the charge
align:start position:0%
do something just with the charge
density and so what they did is writing
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density and so what they did is writing
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density and so what they did is writing
out what we would call a heuristic
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out what we would call a heuristic
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out what we would call a heuristic
functional that is trying to devise
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functional that is trying to devise
align:start position:0%
functional that is trying to devise
a set of terms that would give us the
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a set of terms that would give us the
align:start position:0%
a set of terms that would give us the
energy of a set of electrons in a
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energy of a set of electrons in a
align:start position:0%
energy of a set of electrons in a
potential just as a functional of their
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potential just as a functional of their
align:start position:0%
potential just as a functional of their
charge density and so you know sort of
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charge density and so you know sort of
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charge density and so you know sort of
by now you could sort of think that some
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by now you could sort of think that some
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by now you could sort of think that some
of you know the relevant terms will be
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of you know the relevant terms will be
align:start position:0%
of you know the relevant terms will be
electron-electron interactions electron
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electron-electron interactions electron
align:start position:0%
electron-electron interactions electron
interact and we could write a set of
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interact and we could write a set of
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interact and we could write a set of
electrostatic term like the Hartree term
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electrostatic term like the Hartree term
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electrostatic term like the Hartree term
in the heart or the hartree-fock
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in the heart or the hartree-fock
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in the heart or the hartree-fock
equation that is just a functional of
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equation that is just a functional of
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equation that is just a functional of
the charge density so this is sort of
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the charge density so this is sort of
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the charge density so this is sort of
fairly easy it's also very easy to set
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fairly easy it's also very easy to set
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fairly easy it's also very easy to set
up you know imagine what could be the
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up you know imagine what could be the
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up you know imagine what could be the
interaction of the electrons with an
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interaction of the electrons with an
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interaction of the electrons with an
external potential through the charge
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external potential through the charge
align:start position:0%
external potential through the charge
density will be just the integral of
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density will be just the integral of
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density will be just the integral of
that external potential times the charge
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that external potential times the charge
align:start position:0%
that external potential times the charge
density what becomes really critical is
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density what becomes really critical is
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density what becomes really critical is
you know finding a
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you know finding a
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you know finding a
functional that will give us the quantum
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functional that will give us the quantum
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functional that will give us the quantum
kinetic energy if you think in the
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kinetic energy if you think in the
align:start position:0%
kinetic energy if you think in the
Schrodinger equation the quantum kinetic
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Schrodinger equation the quantum kinetic
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Schrodinger equation the quantum kinetic
energy is really the second derivative
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energy is really the second derivative
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energy is really the second derivative
of the wave function and
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of the wave function and
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of the wave function and
obtaining from a charge density only
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obtaining from a charge density only
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obtaining from a charge density only
some insight into what could be the
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some insight into what could be the
align:start position:0%
some insight into what could be the
second Riv whatever the wavefunction is
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second Riv whatever the wavefunction is
align:start position:0%
second Riv whatever the wavefunction is
very complex if you think for a moment
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very complex if you think for a moment
align:start position:0%
very complex if you think for a moment
at the extreme case of a plane wave okay
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at the extreme case of a plane wave okay
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at the extreme case of a plane wave okay
so a sine and cosine sort of in space
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so a sine and cosine sort of in space
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so a sine and cosine sort of in space
remember the charge density given by a
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remember the charge density given by a
align:start position:0%
remember the charge density given by a
plane wave is a constant we just
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plane wave is a constant we just
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plane wave is a constant we just
multiply the exponential times the
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multiply the exponential times the
align:start position:0%
multiply the exponential times the
company imaginary exponential times its
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company imaginary exponential times its
align:start position:0%
company imaginary exponential times its
complex conjugate that gives us a
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complex conjugate that gives us a
align:start position:0%
complex conjugate that gives us a
constant so all plane waves lead to a
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constant so all plane waves lead to a
align:start position:0%
constant so all plane waves lead to a
constant but obviously the quantum
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constant but obviously the quantum
align:start position:0%
constant but obviously the quantum
kinetic energy of a plane wave depends
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kinetic energy of a plane wave depends
align:start position:0%
kinetic energy of a plane wave depends
on the wave length of that plane wave
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on the wave length of that plane wave
align:start position:0%
on the wave length of that plane wave
because the second derivative is what
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because the second derivative is what
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because the second derivative is what
counts up so what I'm trying to say is
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counts up so what I'm trying to say is
align:start position:0%
counts up so what I'm trying to say is
that when we look at sort of this as a
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that when we look at sort of this as a
align:start position:0%
that when we look at sort of this as a
possible wave function a
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possible wave function a
align:start position:0%
possible wave function a
function say of R and the charge density
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function say of R and the charge density
align:start position:0%
function say of R and the charge density
that comes from this is going to be a
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that comes from this is going to be a
align:start position:0%
that comes from this is going to be a
constant this wave function times this
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constant this wave function times this
align:start position:0%
constant this wave function times this
complex conjugate but the kinetic energy
align:start position:0%
complex conjugate but the kinetic energy
align:start position:0%
complex conjugate but the kinetic energy
of this object
align:start position:0%
of this object
align:start position:0%
of this object
is going to be minus 1/2 K square sorry
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is going to be minus 1/2 K square sorry
align:start position:0%
is going to be minus 1/2 K square sorry
plus 1/2 K square and so there is really
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plus 1/2 K square and so there is really
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plus 1/2 K square and so there is really
not a good way for this extreme case
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not a good way for this extreme case
align:start position:0%
not a good way for this extreme case
that to correlate its charge density to
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that to correlate its charge density to
align:start position:0%
that to correlate its charge density to
the kinetic energy it's an ill-defined
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the kinetic energy it's an ill-defined
align:start position:0%
the kinetic energy it's an ill-defined
problem and this is really the
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problem and this is really the
align:start position:0%
problem and this is really the
difficulty ok so there isn't really a
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difficulty ok so there isn't really a
align:start position:0%
difficulty ok so there isn't really a
good way if you wanted to extract the
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good way if you wanted to extract the
align:start position:0%
good way if you wanted to extract the
information on the second derivative
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information on the second derivative
align:start position:0%
information on the second derivative
from just a charge density
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from just a charge density
align:start position:0%
from just a charge density
no matter sort of this objection they
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no matter sort of this objection they
align:start position:0%
no matter sort of this objection they
tried sort of to find a
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tried sort of to find a
align:start position:0%
tried sort of to find a
reasonable functional so without sort of
align:start position:0%
reasonable functional so without sort of
align:start position:0%
reasonable functional so without sort of
trying to get the exact solution but try
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trying to get the exact solution but try
align:start position:0%
trying to get the exact solution but try
to find a reasonable functional that
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to find a reasonable functional that
align:start position:0%
to find a reasonable functional that
would give us a good estimate to the
align:start position:0%
would give us a good estimate to the
align:start position:0%
would give us a good estimate to the
kinetic the quantum kinetic energy
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kinetic the quantum kinetic energy
align:start position:0%
kinetic the quantum kinetic energy
starting from the charge density and the
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starting from the charge density and the
align:start position:0%
starting from the charge density and the
solution to this problem that is
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solution to this problem that is
align:start position:0%
solution to this problem that is
something very important is what we
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something very important is what we
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something very important is what we
could call a local density approximation
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could call a local density approximation
align:start position:0%
could call a local density approximation
so the problem here is that we ever
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so the problem here is that we ever
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so the problem here is that we ever
known amo genius charge density
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known amo genius charge density
align:start position:0%
known amo genius charge density
everywhere in space and we try to figure
align:start position:0%
everywhere in space and we try to figure
align:start position:0%
everywhere in space and we try to figure
out what could be the quantum kinetic
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out what could be the quantum kinetic
align:start position:0%
out what could be the quantum kinetic
energy of this non-homogeneous problem
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energy of this non-homogeneous problem
align:start position:0%
energy of this non-homogeneous problem
and
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and
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and
set of the approximation that Thomason
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set of the approximation that Thomason
align:start position:0%
set of the approximation that Thomason
Fermi Dida was that are well dividing
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Fermi Dida was that are well dividing
align:start position:0%
Fermi Dida was that are well dividing
this non-homogeneous problem in a set of
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this non-homogeneous problem in a set of
align:start position:0%
this non-homogeneous problem in a set of
sort of infinitesimal volume in space
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sort of infinitesimal volume in space
align:start position:0%
sort of infinitesimal volume in space
and so it's a bit difficult to draw but
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and so it's a bit difficult to draw but
align:start position:0%
and so it's a bit difficult to draw but
suppose you have the density charge
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suppose you have the density charge
align:start position:0%
suppose you have the density charge
density coming from some atom or some
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density coming from some atom or some
align:start position:0%
density coming from some atom or some
molecule this is an
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molecule this is an
align:start position:0%
molecule this is an
non-homogeneous charge density
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non-homogeneous charge density
align:start position:0%
non-homogeneous charge density
distribution now what you do is you
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distribution now what you do is you
align:start position:0%
distribution now what you do is you
divide this in space in such a very
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divide this in space in such a very
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divide this in space in such a very
small infinitesimal if you want volume
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small infinitesimal if you want volume
align:start position:0%
small infinitesimal if you want volume
and
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and
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and
inside each volume the charge density
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inside each volume the charge density
align:start position:0%
inside each volume the charge density
can be approximated as a constant and
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can be approximated as a constant and
align:start position:0%
can be approximated as a constant and
what Thomas and Fermi said is well the
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what Thomas and Fermi said is well the
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what Thomas and Fermi said is well the
contribution coming from this
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contribution coming from this
align:start position:0%
contribution coming from this
infinitesimal volume say the first one
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infinitesimal volume say the first one
align:start position:0%
infinitesimal volume say the first one
to the overall quantum kinetic energy
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to the overall quantum kinetic energy
align:start position:0%
to the overall quantum kinetic energy
will be given by that volume times the
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will be given by that volume times the
align:start position:0%
will be given by that volume times the
kinetic energy density of the
align:start position:0%
kinetic energy density of the
align:start position:0%
kinetic energy density of the
homogeneous electron Gaza at that
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homogeneous electron Gaza at that
align:start position:0%
homogeneous electron Gaza at that
density so if again we partition all
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density so if again we partition all
align:start position:0%
density so if again we partition all
space we could have that you know the
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space we could have that you know the
align:start position:0%
space we could have that you know the
density in this little cube is point 5
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density in this little cube is point 5
align:start position:0%
density in this little cube is point 5
here is point 6 here is point 7 outside
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here is point 6 here is point 7 outside
align:start position:0%
here is point 6 here is point 7 outside
it goes to 0 but we can actually
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it goes to 0 but we can actually
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it goes to 0 but we can actually
calculate in some other way what would
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calculate in some other way what would
align:start position:0%
calculate in some other way what would
be the quantum kinetic energy of a
align:start position:0%
be the quantum kinetic energy of a
align:start position:0%
be the quantum kinetic energy of a
homogeneous electron gas that's a
align:start position:0%
homogeneous electron gas that's a
align:start position:0%
homogeneous electron gas that's a
problem that we can solve if the
align:start position:0%
problem that we can solve if the
align:start position:0%
problem that we can solve if the
homogeneous electron gas is not
align:start position:0%
homogeneous electron gas is not
align:start position:0%
homogeneous electron gas is not
interacting and we can solve it
align:start position:0%
interacting and we can solve it
align:start position:0%
interacting and we can solve it
numerically even if it is interacting so
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numerically even if it is interacting so
align:start position:0%
numerically even if it is interacting so
we can know what is the quantum kinetic
align:start position:0%
we can know what is the quantum kinetic
align:start position:0%
we can know what is the quantum kinetic
energy of a homogeneous gas with density
align:start position:0%
energy of a homogeneous gas with density
align:start position:0%
energy of a homogeneous gas with density
point 5 density point 6 density point 7
align:start position:0%
point 5 density point 6 density point 7
align:start position:0%
point 5 density point 6 density point 7
and so we can also know what would be
align:start position:0%
and so we can also know what would be
align:start position:0%
and so we can also know what would be
the quantum kinetic energy per unit of
align:start position:0%
the quantum kinetic energy per unit of
align:start position:0%
the quantum kinetic energy per unit of
volume of data and so we'll say that
align:start position:0%
volume of data and so we'll say that
align:start position:0%
volume of data and so we'll say that
this non-homogeneous system in blue will
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this non-homogeneous system in blue will
align:start position:0%
this non-homogeneous system in blue will
have an overall quantum kinetic energy
align:start position:0%
have an overall quantum kinetic energy
align:start position:0%
have an overall quantum kinetic energy
that is given really by the integral
align:start position:0%
that is given really by the integral
align:start position:0%
that is given really by the integral
across space and it's written here of
align:start position:0%
across space and it's written here of
align:start position:0%
across space and it's written here of
the quantum kinetic energy of the
align:start position:0%
the quantum kinetic energy of the
align:start position:0%
the quantum kinetic energy of the
homogeneous electron gas integrated over
align:start position:0%
homogeneous electron gas integrated over
align:start position:0%
homogeneous electron gas integrated over
space and say for the non-interacting
align:start position:0%
space and say for the non-interacting
align:start position:0%
space and say for the non-interacting
electrons ASSA is that really very easy
align:start position:0%
electrons ASSA is that really very easy
align:start position:0%
electrons ASSA is that really very easy
to do so if you ever known interacting
align:start position:0%
to do so if you ever known interacting
align:start position:0%
to do so if you ever known interacting
electron gas at a density Rho its
align:start position:0%
electron gas at a density Rho its
align:start position:0%
electron gas at a density Rho its
quantum kinetic energy is just Rho to
align:start position:0%
quantum kinetic energy is just Rho to
align:start position:0%
quantum kinetic energy is just Rho to
the 2/3 that then integrated time the
align:start position:0%
the 2/3 that then integrated time the
align:start position:0%
the 2/3 that then integrated time the
unit volume gives as an Rho to the 5/3
align:start position:0%
unit volume gives as an Rho to the 5/3
align:start position:0%
unit volume gives as an Rho to the 5/3
so by integrating this quantity we would
align:start position:0%
so by integrating this quantity we would
align:start position:0%
so by integrating this quantity we would
get an approximation this approximation
align:start position:0%
get an approximation this approximation
align:start position:0%
get an approximation this approximation
is basically exact in the limit of a
align:start position:0%
is basically exact in the limit of a
align:start position:0%
is basically exact in the limit of a
homogeneous system obviously and it will
align:start position:0%
homogeneous system obviously and it will
align:start position:0%
homogeneous system obviously and it will
be sort of quite good in the limiter of
align:start position:0%
be sort of quite good in the limiter of
align:start position:0%
be sort of quite good in the limiter of
a non homogeneous system the tears are
align:start position:0%
a non homogeneous system the tears are
align:start position:0%
a non homogeneous system the tears are
very slowly changing charge density the
align:start position:0%
very slowly changing charge density the
align:start position:0%
very slowly changing charge density the
more if you want a inhomogeneous your
align:start position:0%
more if you want a inhomogeneous your
align:start position:0%
more if you want a inhomogeneous your
system becomes the less accurate this
align:start position:0%
system becomes the less accurate this
align:start position:0%
system becomes the less accurate this
approximation is and of course something
align:start position:0%
approximation is and of course something
align:start position:0%
approximation is and of course something
like an atom or a molecule is a very
align:start position:0%
like an atom or a molecule is a very
align:start position:0%
like an atom or a molecule is a very
inhomogeneous system you go with the
align:start position:0%
inhomogeneous system you go with the
align:start position:0%
inhomogeneous system you go with the
charge density
align:start position:0%
charge density
align:start position:0%
charge density
that goes from zero to very high volumes
align:start position:0%
that goes from zero to very high volumes
align:start position:0%
that goes from zero to very high volumes
close to the core of the nuclei
align:start position:0%
align:start position:0%
so this is basically the overall on
align:start position:0%
so this is basically the overall on
align:start position:0%
so this is basically the overall on
Saturday overall expression the Thomas
align:start position:0%
Saturday overall expression the Thomas
align:start position:0%
Saturday overall expression the Thomas
and Fermi postulated for the energy of
align:start position:0%
and Fermi postulated for the energy of
align:start position:0%
and Fermi postulated for the energy of
an inhomogeneous system they were saying
align:start position:0%
an inhomogeneous system they were saying
align:start position:0%
an inhomogeneous system they were saying
well suppose that we have a system that
align:start position:0%
well suppose that we have a system that
align:start position:0%
well suppose that we have a system that
there's a certain distribution of charge
align:start position:0%
there's a certain distribution of charge
align:start position:0%
there's a certain distribution of charge
row without trying to solve the
align:start position:0%
row without trying to solve the
align:start position:0%
row without trying to solve the
Schrodinger equation finding out the
align:start position:0%
Schrodinger equation finding out the
align:start position:0%
Schrodinger equation finding out the
wavefunction and sort of go through that
align:start position:0%
wavefunction and sort of go through that
align:start position:0%
wavefunction and sort of go through that
is a very complex many-body router we
align:start position:0%
is a very complex many-body router we
align:start position:0%
is a very complex many-body router we
can actually set up postulate that the
align:start position:0%
can actually set up postulate that the
align:start position:0%
can actually set up postulate that the
energy could be written again as an
align:start position:0%
energy could be written again as an
align:start position:0%
energy could be written again as an
electrostatic energy you see set of each
align:start position:0%
electrostatic energy you see set of each
align:start position:0%
electrostatic energy you see set of each
infinitesimal volume interacting with
align:start position:0%
infinitesimal volume interacting with
align:start position:0%
infinitesimal volume interacting with
each other infinitesimal volume times
align:start position:0%
each other infinitesimal volume times
align:start position:0%
each other infinitesimal volume times
via one over our electrostatic
align:start position:0%
via one over our electrostatic
align:start position:0%
via one over our electrostatic
interaction then we have got an external
align:start position:0%
interaction then we have got an external
align:start position:0%
interaction then we have got an external
potential again it's usually the
align:start position:0%
potential again it's usually the
align:start position:0%
potential again it's usually the
columbic field of the nuclei and so the
align:start position:0%
columbic field of the nuclei and so the
align:start position:0%
columbic field of the nuclei and so the
interaction between the electron and
align:start position:0%
interaction between the electron and
align:start position:0%
interaction between the electron and
that external potential is just
align:start position:0%
that external potential is just
align:start position:0%
that external potential is just
trivially given by Rho times V and the
align:start position:0%
trivially given by Rho times V and the
align:start position:0%
trivially given by Rho times V and the
difficult term the quantum kinetic
align:start position:0%
difficult term the quantum kinetic
align:start position:0%
difficult term the quantum kinetic
energy has been calculated with a local
align:start position:0%
energy has been calculated with a local
align:start position:0%
energy has been calculated with a local
density approximation and this is the
align:start position:0%
density approximation and this is the
align:start position:0%
density approximation and this is the
term that's not going to be very good
align:start position:0%
term that's not going to be very good
align:start position:0%
term that's not going to be very good
again because it's very difficult to
align:start position:0%
again because it's very difficult to
align:start position:0%
again because it's very difficult to
figure out what could be the curvature
align:start position:0%
figure out what could be the curvature
align:start position:0%
figure out what could be the curvature
of our wave function
align:start position:0%
of our wave function
align:start position:0%
of our wave function
just from the density that that wave
align:start position:0%
just from the density that that wave
align:start position:0%
just from the density that that wave
function produces but anyhow this is a
align:start position:0%
function produces but anyhow this is a
align:start position:0%
function produces but anyhow this is a
very simple expression to deal with so
align:start position:0%
very simple expression to deal with so
align:start position:0%
very simple expression to deal with so
for any external potential V we can try
align:start position:0%
for any external potential V we can try
align:start position:0%
for any external potential V we can try
to find out the row that minimizes this
align:start position:0%
to find out the row that minimizes this
align:start position:0%
to find out the row that minimizes this
expression and this will be our thomas
align:start position:0%
expression and this will be our thomas
align:start position:0%
expression and this will be our thomas
fermi solution
align:start position:0%
align:start position:0%
there are obviously a number of problems
align:start position:0%
there are obviously a number of problems
align:start position:0%
there are obviously a number of problems
are showing a moment and example of what
align:start position:0%
are showing a moment and example of what
align:start position:0%
are showing a moment and example of what
the thomas fiering solution would give
align:start position:0%
the thomas fiering solution would give
align:start position:0%
the thomas fiering solution would give
to an atom first of all i mean there is
align:start position:0%
to an atom first of all i mean there is
align:start position:0%
to an atom first of all i mean there is
really no theoretical basis to this it's
align:start position:0%
really no theoretical basis to this it's
align:start position:0%
really no theoretical basis to this it's
what we call a heuristic derivation
align:start position:0%
what we call a heuristic derivation
align:start position:0%
what we call a heuristic derivation
Thomas an Fermi just wrote out what
align:start position:0%
Thomas an Fermi just wrote out what
align:start position:0%
Thomas an Fermi just wrote out what
could be a regional energy functional
align:start position:0%
could be a regional energy functional
align:start position:0%
could be a regional energy functional
and then try to sort of see what results
align:start position:0%
and then try to sort of see what results
align:start position:0%
and then try to sort of see what results
it would give but there hasn't been any
align:start position:0%
it would give but there hasn't been any
align:start position:0%
it would give but there hasn't been any
kind of you know formal derivation of
align:start position:0%
kind of you know formal derivation of
align:start position:0%
kind of you know formal derivation of
that functional it's not like the
align:start position:0%
that functional it's not like the
align:start position:0%
that functional it's not like the
hartree-fock equation that sort of
align:start position:0%
hartree-fock equation that sort of
align:start position:0%
hartree-fock equation that sort of
derive just with some analysis from the
align:start position:0%
derive just with some analysis from the
align:start position:0%
derive just with some analysis from the
variational principle
align:start position:0%
variational principle
align:start position:0%
variational principle
another problem is that again it doesn't
align:start position:0%
another problem is that again it doesn't
align:start position:0%
another problem is that again it doesn't
really sort of introduce the concept of
align:start position:0%
really sort of introduce the concept of
align:start position:0%
really sort of introduce the concept of
anti symmetry that fermions need to have
align:start position:0%
anti symmetry that fermions need to have
align:start position:0%
anti symmetry that fermions need to have
the fact that they many-body wave
align:start position:0%
the fact that they many-body wave
align:start position:0%
the fact that they many-body wave
function needs to be antisymmetric upon
align:start position:0%
function needs to be antisymmetric upon
align:start position:0%
function needs to be antisymmetric upon
exchange but you know there is no
align:start position:0%
exchange but you know there is no
align:start position:0%
exchange but you know there is no
conceptual problem in adding and
align:start position:0%
conceptual problem in adding and
align:start position:0%
conceptual problem in adding and
exchange energy to the previous
align:start position:0%
exchange energy to the previous
align:start position:0%
exchange energy to the previous
functional using the same concept that
align:start position:0%
functional using the same concept that
align:start position:0%
functional using the same concept that
the same idea of local density
align:start position:0%
the same idea of local density
align:start position:0%
the same idea of local density
approximation suppose that we want to
align:start position:0%
approximation suppose that we want to
align:start position:0%
approximation suppose that we want to
add an exchange term well we could look
align:start position:0%
add an exchange term well we could look
align:start position:0%
add an exchange term well we could look
at what is the exchange energy coming
align:start position:0%
at what is the exchange energy coming
align:start position:0%
at what is the exchange energy coming
from the hartree-fock equations say for
align:start position:0%
from the hartree-fock equations say for
align:start position:0%
from the hartree-fock equations say for
a homogeneous electron gaza and that
align:start position:0%
a homogeneous electron gaza and that
align:start position:0%
a homogeneous electron gaza and that
gives us a row to the one-third term and
align:start position:0%
gives us a row to the one-third term and
align:start position:0%
gives us a row to the one-third term and
that's basically the exchange energy
align:start position:0%
that's basically the exchange energy
align:start position:0%
that's basically the exchange energy
density and so for an inhomogeneous
align:start position:0%
density and so for an inhomogeneous
align:start position:0%
density and so for an inhomogeneous
system we are going to sort of
align:start position:0%
system we are going to sort of
align:start position:0%
system we are going to sort of
approximate its overall exchange energy
align:start position:0%
approximate its overall exchange energy
align:start position:0%
approximate its overall exchange energy
just by taking the integral of that
align:start position:0%
just by taking the integral of that
align:start position:0%
just by taking the integral of that
energy density that is one further times
align:start position:0%
energy density that is one further times
align:start position:0%
energy density that is one further times
the sort of local value of the charge
align:start position:0%
the sort of local value of the charge
align:start position:0%
the sort of local value of the charge
density and so we have a row to the 4/3
align:start position:0%
density and so we have a row to the 4/3
align:start position:0%
density and so we have a row to the 4/3
and so again it's a local density
align:start position:0%
and so again it's a local density
align:start position:0%
and so again it's a local density
approximation
align:start position:0%
approximation
align:start position:0%
approximation
they sort of great consequence of having
align:start position:0%
they sort of great consequence of having
align:start position:0%
they sort of great consequence of having
this
align:start position:0%
this
align:start position:0%
this
energy functional that depends only on R
align:start position:0%
energy functional that depends only on R
align:start position:0%
energy functional that depends only on R
is that it is absolutely inexpensive
align:start position:0%
is that it is absolutely inexpensive
align:start position:0%
is that it is absolutely inexpensive
from the computational point of view the
align:start position:0%
from the computational point of view the
align:start position:0%
from the computational point of view the
only variable that we need to be
align:start position:0%
only variable that we need to be
align:start position:0%
only variable that we need to be
concerned with is just
align:start position:0%
concerned with is just
align:start position:0%
concerned with is just
escalara as a function of three
align:start position:0%
escalara as a function of three
align:start position:0%
escalara as a function of three
coordinates that is the density as a
align:start position:0%
coordinates that is the density as a
align:start position:0%
coordinates that is the density as a
function of Rho and it's what we call a
align:start position:0%
function of Rho and it's what we call a
align:start position:0%
function of Rho and it's what we call a
linear scaling system if you double the
align:start position:0%
linear scaling system if you double the
align:start position:0%
linear scaling system if you double the
size of your system the computational
align:start position:0%
size of your system the computational
align:start position:0%
size of your system the computational
complexity just becomes double so it has
align:start position:0%
complexity just becomes double so it has
align:start position:0%
complexity just becomes double so it has
a lot of very good things but it got a
align:start position:0%
a lot of very good things but it got a
align:start position:0%
a lot of very good things but it got a
fundamental defect because of that
align:start position:0%
fundamental defect because of that
align:start position:0%
fundamental defect because of that
approximation in the kinetic energy it
align:start position:0%
approximation in the kinetic energy it
align:start position:0%
approximation in the kinetic energy it
actually does a very poor job in a
align:start position:0%
actually does a very poor job in a
align:start position:0%
actually does a very poor job in a
describing a non homogeneous system so
align:start position:0%
describing a non homogeneous system so
align:start position:0%
describing a non homogeneous system so
it would work reasonably well for
align:start position:0%
it would work reasonably well for
align:start position:0%
it would work reasonably well for
something like a mental suppose that you
align:start position:0%
something like a mental suppose that you
align:start position:0%
something like a mental suppose that you
want to describe a sodium or suppose you
align:start position:0%
want to describe a sodium or suppose you
align:start position:0%
want to describe a sodium or suppose you
want to describe aluminum those are
align:start position:0%
want to describe aluminum those are
align:start position:0%
want to describe aluminum those are
system in which the valence electron
align:start position:0%
system in which the valence electron
align:start position:0%
system in which the valence electron
produce a charge density that is very
align:start position:0%
produce a charge density that is very
align:start position:0%
produce a charge density that is very
homogeneous so a thomas fermi approach
align:start position:0%
homogeneous so a thomas fermi approach
align:start position:0%
homogeneous so a thomas fermi approach
could actually work well and it's
align:start position:0%
could actually work well and it's
align:start position:0%
could actually work well and it's
actually been used even very recently
align:start position:0%
actually been used even very recently
align:start position:0%
actually been used even very recently
sort of quite successfully to describe
align:start position:0%
sort of quite successfully to describe
align:start position:0%
sort of quite successfully to describe
problems like the surfaces of lithium
align:start position:0%
problems like the surfaces of lithium
align:start position:0%
problems like the surfaces of lithium
the surfaces of aluminum what happens
align:start position:0%
the surfaces of aluminum what happens
align:start position:0%
the surfaces of aluminum what happens
say what when these simple metals melt
align:start position:0%
say what when these simple metals melt
align:start position:0%
say what when these simple metals melt
what happens to the sort of formation of
align:start position:0%
what happens to the sort of formation of
align:start position:0%
what happens to the sort of formation of
defects in aluminum so there are a
align:start position:0%
defects in aluminum so there are a
align:start position:0%
defects in aluminum so there are a
number of successes but sort of you know
align:start position:0%
number of successes but sort of you know
align:start position:0%
number of successes but sort of you know
clear example of what goes wrong is if
align:start position:0%
clear example of what goes wrong is if
align:start position:0%
clear example of what goes wrong is if
we study an inhomogeneous system like
align:start position:0%
we study an inhomogeneous system like
align:start position:0%
we study an inhomogeneous system like
the argon atom and again if we think at
align:start position:0%
the argon atom and again if we think at
align:start position:0%
the argon atom and again if we think at
the charge density of the argon atom as
align:start position:0%
the charge density of the argon atom as
align:start position:0%
the charge density of the argon atom as
a function say of the radial distance
align:start position:0%
a function say of the radial distance
align:start position:0%
a function say of the radial distance
from the centre from the nucleus well it
align:start position:0%
from the centre from the nucleus well it
align:start position:0%
from the centre from the nucleus well it
will look something like this we have
align:start position:0%
will look something like this we have
align:start position:0%
will look something like this we have
first a 1s and then we have the 2s and
align:start position:0%
first a 1s and then we have the 2s and
align:start position:0%
first a 1s and then we have the 2s and
the 2p shells okay this is somewhat a
align:start position:0%
the 2p shells okay this is somewhat a
align:start position:0%
the 2p shells okay this is somewhat a
poor depiction of that charge density if
align:start position:0%
poor depiction of that charge density if
align:start position:0%
poor depiction of that charge density if
we try to solve the argon atom with a
align:start position:0%
we try to solve the argon atom with a
align:start position:0%
we try to solve the argon atom with a
thomas fermi approach all these sort of
align:start position:0%
thomas fermi approach all these sort of
align:start position:0%
thomas fermi approach all these sort of
you know fine structure of the core
align:start position:0%
you know fine structure of the core
align:start position:0%
you know fine structure of the core
shells in the atoms is completely washed
align:start position:0%
shells in the atoms is completely washed
align:start position:0%
shells in the atoms is completely washed
out okay so it gives you a reasonable
align:start position:0%
out okay so it gives you a reasonable
align:start position:0%
out okay so it gives you a reasonable
approximation and a sort of an
align:start position:0%
approximation and a sort of an
align:start position:0%
approximation and a sort of an
appropriate decay of the charge density
align:start position:0%
appropriate decay of the charge density
align:start position:0%
appropriate decay of the charge density
as we move far away but a lot of those
align:start position:0%
as we move far away but a lot of those
align:start position:0%
as we move far away but a lot of those
details have completely disappeared and
align:start position:0%
details have completely disappeared and
align:start position:0%
details have completely disappeared and
for this reason really the Thomas film
align:start position:0%
for this reason really the Thomas film
align:start position:0%
for this reason really the Thomas film
yeah
align:start position:0%
yeah
align:start position:0%
yeah
wasn't developed beyond the firt is a
align:start position:0%
wasn't developed beyond the firt is a
align:start position:0%
wasn't developed beyond the firt is a
bathroom sort of you know some of this
align:start position:0%
bathroom sort of you know some of this
align:start position:0%
bathroom sort of you know some of this
recent application for the very specific
align:start position:0%
recent application for the very specific
align:start position:0%
recent application for the very specific
case of solids that have a very ominous
align:start position:0%
case of solids that have a very ominous
align:start position:0%
case of solids that have a very ominous
charge density the reason why we
align:start position:0%
charge density the reason why we
align:start position:0%
charge density the reason why we
described it here is that because in
align:start position:0%
described it here is that because in
align:start position:0%
described it here is that because in
many ways it's the grandfather of the
align:start position:0%
many ways it's the grandfather of the
align:start position:0%
many ways it's the grandfather of the
ideas that were developed in the 60s in
align:start position:0%
ideas that were developed in the 60s in
align:start position:0%
ideas that were developed in the 60s in
that's the functional theory and in
align:start position:0%
that's the functional theory and in
align:start position:0%
that's the functional theory and in
particular the idea that for a moment we
align:start position:0%
particular the idea that for a moment we
align:start position:0%
particular the idea that for a moment we
should focus not on the wavefunction but
align:start position:0%
should focus not on the wavefunction but
align:start position:0%
should focus not on the wavefunction but
on the charge density of the system as
align:start position:0%
on the charge density of the system as
align:start position:0%
on the charge density of the system as
the key ingredient
align:start position:0%
the key ingredient
align:start position:0%
the key ingredient
the great difference between the Thomas
align:start position:0%
the great difference between the Thomas
align:start position:0%
the great difference between the Thomas
Fermi approach and density functional
align:start position:0%
Fermi approach and density functional
align:start position:0%
Fermi approach and density functional
theory is that density functional theory
align:start position:0%
theory is that density functional theory
align:start position:0%
theory is that density functional theory
actually is a theory it starts with some
align:start position:0%
actually is a theory it starts with some
align:start position:0%
actually is a theory it starts with some
theorems that are proven and then it
align:start position:0%
theorems that are proven and then it
align:start position:0%
theorems that are proven and then it
shows what are the form of the equations
align:start position:0%
shows what are the form of the equations
align:start position:0%
shows what are the form of the equations
that say a charge density need to
align:start position:0%
that say a charge density need to
align:start position:0%
that say a charge density need to
satisfy in order to solve exactly the
align:start position:0%
satisfy in order to solve exactly the
align:start position:0%
satisfy in order to solve exactly the
problem so in many ways the inste
align:start position:0%
problem so in many ways the inste
align:start position:0%
problem so in many ways the inste
functional theory is an in principle at
align:start position:0%
functional theory is an in principle at
align:start position:0%
functional theory is an in principle at
least an exact theory it's a top writes
align:start position:0%
least an exact theory it's a top writes
align:start position:0%
least an exact theory it's a top writes
out what are the equation that the
align:start position:0%
out what are the equation that the
align:start position:0%
out what are the equation that the
charge density needs to satisfy and
align:start position:0%
charge density needs to satisfy and
align:start position:0%
charge density needs to satisfy and
those are absolutely equivalent to a
align:start position:0%
those are absolutely equivalent to a
align:start position:0%
those are absolutely equivalent to a
Schrodinger equation for the wave
align:start position:0%
Schrodinger equation for the wave
align:start position:0%
Schrodinger equation for the wave
function there are some difficulties and
align:start position:0%
function there are some difficulties and
align:start position:0%
function there are some difficulties and
this is what we are going to sort of go
align:start position:0%
this is what we are going to sort of go
align:start position:0%
this is what we are going to sort of go
into right now but sort of let me first
align:start position:0%
into right now but sort of let me first
align:start position:0%
into right now but sort of let me first
give you the conceptual framework of
align:start position:0%
give you the conceptual framework of
align:start position:0%
give you the conceptual framework of
density functional theory and sort of
align:start position:0%
density functional theory and sort of
align:start position:0%
density functional theory and sort of
how it was derived and as usual we
align:start position:0%
how it was derived and as usual we
align:start position:0%
how it was derived and as usual we
started from the Schrodinger equation
align:start position:0%
started from the Schrodinger equation
align:start position:0%
started from the Schrodinger equation
okay so we start from the idea that in
align:start position:0%
okay so we start from the idea that in
align:start position:0%
okay so we start from the idea that in
quantum mechanics for any given external
align:start position:0%
quantum mechanics for any given external
align:start position:0%
quantum mechanics for any given external
potential you have a well-defined
align:start position:0%
potential you have a well-defined
align:start position:0%
potential you have a well-defined
differential equation okay it's sort of
align:start position:0%
differential equation okay it's sort of
align:start position:0%
differential equation okay it's sort of
very complex it describes a many-body
align:start position:0%
very complex it describes a many-body
align:start position:0%
very complex it describes a many-body
wave function so in most practical cases
align:start position:0%
wave function so in most practical cases
align:start position:0%
wave function so in most practical cases
we might not be able to solve it but
align:start position:0%
we might not be able to solve it but
align:start position:0%
we might not be able to solve it but
everything is well-defined you have an
align:start position:0%
everything is well-defined you have an
align:start position:0%
everything is well-defined you have an
external potential you have the
align:start position:0%
external potential you have the
align:start position:0%
external potential you have the
differential equation that the many-body
align:start position:0%
differential equation that the many-body
align:start position:0%
differential equation that the many-body
wave function needs to satisfy and so in
align:start position:0%
wave function needs to satisfy and so in
align:start position:0%
wave function needs to satisfy and so in
principle you have the solution and so
align:start position:0%
principle you have the solution and so
align:start position:0%
principle you have the solution and so
in that sense that sort of you know the
align:start position:0%
in that sense that sort of you know the
align:start position:0%
in that sense that sort of you know the
first statement here is summarized for a
align:start position:0%
first statement here is summarized for a
align:start position:0%
first statement here is summarized for a
given external potential and knowing how
align:start position:0%
given external potential and knowing how
align:start position:0%
given external potential and knowing how
many electrons are going to fill this
align:start position:0%
many electrons are going to fill this
align:start position:0%
many electrons are going to fill this
potential our quantum problem is
align:start position:0%
potential our quantum problem is
align:start position:0%
potential our quantum problem is
formally completely defined in principle
align:start position:0%
formally completely defined in principle
align:start position:0%
formally completely defined in principle
the solution exists unique we may not be
align:start position:0%
the solution exists unique we may not be
align:start position:0%
the solution exists unique we may not be
able to calculate it but it exists and
align:start position:0%
able to calculate it but it exists and
align:start position:0%
able to calculate it but it exists and
once we know the many-body wave function
align:start position:0%
once we know the many-body wave function
align:start position:0%
once we know the many-body wave function
that solution we know everything about
align:start position:0%
that solution we know everything about
align:start position:0%
that solution we know everything about
our quantum system okay so this is if
align:start position:0%
our quantum system okay so this is if
align:start position:0%
our quantum system okay so this is if
you want the trivial part of the
align:start position:0%
you want the trivial part of the
align:start position:0%
you want the trivial part of the
conclusion that is given an external
align:start position:0%
conclusion that is given an external
align:start position:0%
conclusion that is given an external
potential we find by the shading
align:start position:0%
potential we find by the shading
align:start position:0%
potential we find by the shading
equation the wave function the wave
align:start position:0%
equation the wave function the wave
align:start position:0%
equation the wave function the wave
function determine all the properties of
align:start position:0%
function determine all the properties of
align:start position:0%
function determine all the properties of
our system and in particular determine
align:start position:0%
our system and in particular determine
align:start position:0%
our system and in particular determine
the ground state charge density so there
align:start position:0%
the ground state charge density so there
align:start position:0%
the ground state charge density so there
is a unique pathway that starts from the
align:start position:0%
is a unique pathway that starts from the
align:start position:0%
is a unique pathway that starts from the
external potential and leads us to the
align:start position:0%
external potential and leads us to the
align:start position:0%
external potential and leads us to the
charge density the ground state charge
align:start position:0%
charge density the ground state charge
align:start position:0%
charge density the ground state charge
density once you have defined a
align:start position:0%
density once you have defined a
align:start position:0%
density once you have defined a
potential you in principle have uniquely
align:start position:0%
potential you in principle have uniquely
align:start position:0%
potential you in principle have uniquely
defined what is the ground state charge
align:start position:0%
defined what is the ground state charge
align:start position:0%
defined what is the ground state charge
density of your system and so in that
align:start position:0%
density of your system and so in that
align:start position:0%
density of your system and so in that
sense we say that the ground state
align:start position:0%
sense we say that the ground state
align:start position:0%
sense we say that the ground state
charge density the ground state energy
align:start position:0%
charge density the ground state energy
align:start position:0%
charge density the ground state energy
and all the properties of our system are
align:start position:0%
and all the properties of our system are
align:start position:0%
and all the properties of our system are
in some complex way a functional of our
align:start position:0%
in some complex way a functional of our
align:start position:0%
in some complex way a functional of our
external potential and the number of
align:start position:0%
external potential and the number of
align:start position:0%
external potential and the number of
electrons functional again you know can
align:start position:0%
electrons functional again you know can
align:start position:0%
electrons functional again you know can
be anything and in this case it goes
align:start position:0%
be anything and in this case it goes
align:start position:0%
be anything and in this case it goes
through the Schrodinger equation nothing
align:start position:0%
through the Schrodinger equation nothing
align:start position:0%
through the Schrodinger equation nothing
sort of complex at this at this point
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sort of complex at this at this point
align:start position:0%
sort of complex at this at this point
the sort of remarkable result that no
align:start position:0%
the sort of remarkable result that no
align:start position:0%
the sort of remarkable result that no
one had set of you know figured out
align:start position:0%
one had set of you know figured out
align:start position:0%
one had set of you know figured out
between a 1964 and 1965 is that the
align:start position:0%
between a 1964 and 1965 is that the
align:start position:0%
between a 1964 and 1965 is that the
opposite is also true and it's not
align:start position:0%
opposite is also true and it's not
align:start position:0%
opposite is also true and it's not
trivial at all so what hohenberg and
align:start position:0%
trivial at all so what hohenberg and
align:start position:0%
trivial at all so what hohenberg and
Cohn stated the first actually in 1964
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Cohn stated the first actually in 1964
align:start position:0%
Cohn stated the first actually in 1964
was this that the ground state charge
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was this that the ground state charge
align:start position:0%
was this that the ground state charge
density is a
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density is a
align:start position:0%
density is a
fundamental quantity
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fundamental quantity
align:start position:0%
fundamental quantity
as fundamental as the external potential
align:start position:0%
as fundamental as the external potential
align:start position:0%
as fundamental as the external potential
and in particular not only the external
align:start position:0%
and in particular not only the external
align:start position:0%
and in particular not only the external
potential the terms uniquely the ground
align:start position:0%
potential the terms uniquely the ground
align:start position:0%
potential the terms uniquely the ground
state charge density of yours system but
align:start position:0%
state charge density of yours system but
align:start position:0%
state charge density of yours system but
also the vice versa is true that is
align:start position:0%
also the vice versa is true that is
align:start position:0%
also the vice versa is true that is
given a ground state charge density in
align:start position:0%
given a ground state charge density in
align:start position:0%
given a ground state charge density in
principle one can prove that there is a
align:start position:0%
principle one can prove that there is a
align:start position:0%
principle one can prove that there is a
unique
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unique
align:start position:0%
unique
external potential for which that ground
align:start position:0%
external potential for which that ground
align:start position:0%
external potential for which that ground
state charge density is the ground state
align:start position:0%
state charge density is the ground state
align:start position:0%
state charge density is the ground state
solution for that external potential so
align:start position:0%
solution for that external potential so
align:start position:0%
solution for that external potential so
if you have the external potential
align:start position:0%
if you have the external potential
align:start position:0%
if you have the external potential
conceptually it's trivial to go through
align:start position:0%
conceptually it's trivial to go through
align:start position:0%
conceptually it's trivial to go through
the Schrodinger equation and its
align:start position:0%
the Schrodinger equation and its
align:start position:0%
the Schrodinger equation and its
solution to the charge density what
align:start position:0%
solution to the charge density what
align:start position:0%
solution to the charge density what
hohenberg and corner are telling us and
align:start position:0%
hohenberg and corner are telling us and
align:start position:0%
hohenberg and corner are telling us and
I'll just show you a sketch of the proof
align:start position:0%
I'll just show you a sketch of the proof
align:start position:0%
I'll just show you a sketch of the proof
in a moment is that in principle if
align:start position:0%
in a moment is that in principle if
align:start position:0%
in a moment is that in principle if
someone is giving you a charge density
align:start position:0%
someone is giving you a charge density
align:start position:0%
someone is giving you a charge density
and is telling you this charge density
align:start position:0%
and is telling you this charge density
align:start position:0%
and is telling you this charge density
is the ground state charge density of a
align:start position:0%
is the ground state charge density of a
align:start position:0%
is the ground state charge density of a
number of electrons and electrons in an
align:start position:0%
number of electrons and electrons in an
align:start position:0%
number of electrons and electrons in an
external potential in principle what is
align:start position:0%
external potential in principle what is
align:start position:0%
external potential in principle what is
that external potential is an
align:start position:0%
that external potential is an
align:start position:0%
that external potential is an
information that is completely contained
align:start position:0%
information that is completely contained
align:start position:0%
information that is completely contained
into the charge density okay and it's
align:start position:0%
into the charge density okay and it's
align:start position:0%
into the charge density okay and it's
not contained in a trivial way it's not
align:start position:0%
not contained in a trivial way it's not
align:start position:0%
not contained in a trivial way it's not
that you can look at a ground state
align:start position:0%
that you can look at a ground state
align:start position:0%
that you can look at a ground state
charge density and guess what the
align:start position:0%
charge density and guess what the
align:start position:0%
charge density and guess what the
external potential is and that's where
align:start position:0%
external potential is and that's where
align:start position:0%
external potential is and that's where
all the complexity of practical density
align:start position:0%
all the complexity of practical density
align:start position:0%
all the complexity of practical density
functional Theory comes but from the
align:start position:0%
functional Theory comes but from the
align:start position:0%
functional Theory comes but from the
conceptual and mathematical point of
align:start position:0%
conceptual and mathematical point of
align:start position:0%
conceptual and mathematical point of
view these two quantities are absolutely
align:start position:0%
view these two quantities are absolutely
align:start position:0%
view these two quantities are absolutely
equivalent from one you get the other
align:start position:0%
equivalent from one you get the other
align:start position:0%
equivalent from one you get the other
and vice versa and
align:start position:0%
and vice versa and
align:start position:0%
and vice versa and
the ascent of
align:start position:0%
the ascent of
align:start position:0%
the ascent of
vice versa was not trivial and that is
align:start position:0%
vice versa was not trivial and that is
align:start position:0%
vice versa was not trivial and that is
sort of you know what is contained in
align:start position:0%
sort of you know what is contained in
align:start position:0%
sort of you know what is contained in
the so called first hohenberg and korn
align:start position:0%
the so called first hohenberg and korn
align:start position:0%
the so called first hohenberg and korn
problem I I won't go through the
align:start position:0%
problem I I won't go through the
align:start position:0%
problem I I won't go through the
derivation it's actually very simple
align:start position:0%
derivation it's actually very simple
align:start position:0%
derivation it's actually very simple
I've printed it here in case you sort of
align:start position:0%
I've printed it here in case you sort of
align:start position:0%
I've printed it here in case you sort of
want to read it but it's basically is a
align:start position:0%
want to read it but it's basically is a
align:start position:0%
want to read it but it's basically is a
derivation and absurdum what they are
align:start position:0%
derivation and absurdum what they are
align:start position:0%
derivation and absurdum what they are
saying is that if that external
align:start position:0%
saying is that if that external
align:start position:0%
saying is that if that external
potential were not unique if there were
align:start position:0%
potential were not unique if there were
align:start position:0%
potential were not unique if there were
two external potential that were
align:start position:0%
two external potential that were
align:start position:0%
two external potential that were
different and would give the same ground
align:start position:0%
different and would give the same ground
align:start position:0%
different and would give the same ground
state energy we would get to an absurdum
align:start position:0%
state energy we would get to an absurdum
align:start position:0%
state energy we would get to an absurdum
okay so typical mathematical
align:start position:0%
okay so typical mathematical
align:start position:0%
okay so typical mathematical
demonstration we suppose that there are
align:start position:0%
demonstration we suppose that there are
align:start position:0%
demonstration we suppose that there are
two different external potential that
align:start position:0%
two different external potential that
align:start position:0%
two different external potential that
give the same ground state as density
align:start position:0%
give the same ground state as density
align:start position:0%
give the same ground state as density
and we show that we arrive to a
align:start position:0%
and we show that we arrive to a
align:start position:0%
and we show that we arrive to a
conclusion that doesn't make sense so
align:start position:0%
conclusion that doesn't make sense so
align:start position:0%
conclusion that doesn't make sense so
there can be only a single external
align:start position:0%
there can be only a single external
align:start position:0%
there can be only a single external
potential and that's the proof and again
align:start position:0%
potential and that's the proof and again
align:start position:0%
potential and that's the proof and again
it wasn't trivial I mean if you wanted a
align:start position:0%
it wasn't trivial I mean if you wanted a
align:start position:0%
it wasn't trivial I mean if you wanted a
very basic statement but it took 40
align:start position:0%
very basic statement but it took 40
align:start position:0%
very basic statement but it took 40
years to be formulated and if actually
align:start position:0%
years to be formulated and if actually
align:start position:0%
years to be formulated and if actually
not true in other cases that you know to
align:start position:0%
not true in other cases that you know to
align:start position:0%
not true in other cases that you know to
first glance look very similar suppose
align:start position:0%
first glance look very similar suppose
align:start position:0%
first glance look very similar suppose
that for a moment we want to discuss
align:start position:0%
that for a moment we want to discuss
align:start position:0%
that for a moment we want to discuss
excited states you could say well if I
align:start position:0%
excited states you could say well if I
align:start position:0%
excited states you could say well if I
have a charge density and I say this is
align:start position:0%
have a charge density and I say this is
align:start position:0%
have a charge density and I say this is
an excited density of an excited
align:start position:0%
an excited density of an excited
align:start position:0%
an excited density of an excited
electronic state maybe I could also
align:start position:0%
electronic state maybe I could also
align:start position:0%
electronic state maybe I could also
recover the potential that has generated
align:start position:0%
recover the potential that has generated
align:start position:0%
recover the potential that has generated
that and that's not true actually so
align:start position:0%
that and that's not true actually so
align:start position:0%
that and that's not true actually so
there are sort of a number of cases in
align:start position:0%
there are sort of a number of cases in
align:start position:0%
there are sort of a number of cases in
which this is not true but for this
align:start position:0%
which this is not true but for this
align:start position:0%
which this is not true but for this
fundamental set of relation between the
align:start position:0%
fundamental set of relation between the
align:start position:0%
fundamental set of relation between the
charge density of the ground state and
align:start position:0%
charge density of the ground state and
align:start position:0%
charge density of the ground state and
external potential this is true so we
align:start position:0%
external potential this is true so we
align:start position:0%
external potential this is true so we
have sort of moved away now our
align:start position:0%
have sort of moved away now our
align:start position:0%
have sort of moved away now our
attention it's not any more than any
align:start position:0%
attention it's not any more than any
align:start position:0%
attention it's not any more than any
body wave function that we want to focus
align:start position:0%
body wave function that we want to focus
align:start position:0%
body wave function that we want to focus
but is the charge density the charge
align:start position:0%
but is the charge density the charge
align:start position:0%
but is the charge density the charge
density is as much a fundamental
align:start position:0%
density is as much a fundamental
align:start position:0%
density is as much a fundamental
variable of our problem is not a derived
align:start position:0%
variable of our problem is not a derived
align:start position:0%
variable of our problem is not a derived
variable it's not something that comes
align:start position:0%
variable it's not something that comes
align:start position:0%
variable it's not something that comes
from the wave function but is something
align:start position:0%
from the wave function but is something
align:start position:0%
from the wave function but is something
that we can actually focus all our
align:start position:0%
that we can actually focus all our
align:start position:0%
that we can actually focus all our
attention into and now
align:start position:0%
attention into and now
align:start position:0%
attention into and now
we need to find the equivalent of the
align:start position:0%
we need to find the equivalent of the
align:start position:0%
we need to find the equivalent of the
Schrodinger equation for the charge
align:start position:0%
Schrodinger equation for the charge
align:start position:0%
Schrodinger equation for the charge
density this is what shredding had done
align:start position:0%
density this is what shredding had done
align:start position:0%
density this is what shredding had done
in the 20s in 1925 he said this is the
align:start position:0%
in the 20s in 1925 he said this is the
align:start position:0%
in the 20s in 1925 he said this is the
equation that quantum objects satisfy
align:start position:0%
equation that quantum objects satisfy
align:start position:0%
equation that quantum objects satisfy
and I'll call it the Schrodinger
align:start position:0%
and I'll call it the Schrodinger
align:start position:0%
and I'll call it the Schrodinger
equation now hohenberg ancona has shown
align:start position:0%
equation now hohenberg ancona has shown
align:start position:0%
equation now hohenberg ancona has shown
that we don't need to think in terms of
align:start position:0%
that we don't need to think in terms of
align:start position:0%
that we don't need to think in terms of
the wave function we can think in terms
align:start position:0%
the wave function we can think in terms
align:start position:0%
the wave function we can think in terms
of the charge density as being the
align:start position:0%
of the charge density as being the
align:start position:0%
of the charge density as being the
fundamental descriptor of our quantum
align:start position:0%
fundamental descriptor of our quantum
align:start position:0%
fundamental descriptor of our quantum
system what is life that they need to
align:start position:0%
system what is life that they need to
align:start position:0%
system what is life that they need to
show me that there is an equivalent of
align:start position:0%
show me that there is an equivalent of
align:start position:0%
show me that there is an equivalent of
the shading equation that is we can
align:start position:0%
the shading equation that is we can
align:start position:0%
the shading equation that is we can
write a
align:start position:0%
write a
align:start position:0%
write a
density equation that is a sort of what
align:start position:0%
density equation that is a sort of what
align:start position:0%
density equation that is a sort of what
will give me the ground state and sort
align:start position:0%
will give me the ground state and sort
align:start position:0%
will give me the ground state and sort
of all the properties of the system and
align:start position:0%
of all the properties of the system and
align:start position:0%
of all the properties of the system and
that's really the second hohenberg and
align:start position:0%
that's really the second hohenberg and
align:start position:0%
that's really the second hohenberg and
corner theorem that is really writing
align:start position:0%
corner theorem that is really writing
align:start position:0%
corner theorem that is really writing
out the aquiver the concept one of the
align:start position:0%
out the aquiver the concept one of the
align:start position:0%
out the aquiver the concept one of the
shading an equation for the charge
align:start position:0%
shading an equation for the charge
align:start position:0%
shading an equation for the charge
density and now sort of it becomes
align:start position:0%
density and now sort of it becomes
align:start position:0%
density and now sort of it becomes
fairly conceptual okay so this is a the
align:start position:0%
fairly conceptual okay so this is a the
align:start position:0%
fairly conceptual okay so this is a the
procedure
align:start position:0%
procedure
align:start position:0%
procedure
we and all of this in the next few
align:start position:0%
we and all of this in the next few
align:start position:0%
we and all of this in the next few
slides is still a conceptual procedure
align:start position:0%
slides is still a conceptual procedure
align:start position:0%
slides is still a conceptual procedure
it will describe objects that are
align:start position:0%
it will describe objects that are
align:start position:0%
it will describe objects that are
well-defined
align:start position:0%
well-defined
align:start position:0%
well-defined
in principle that are conceptually
align:start position:0%
in principle that are conceptually
align:start position:0%
in principle that are conceptually
well-defined but we still don't have a
align:start position:0%
well-defined but we still don't have a
align:start position:0%
well-defined but we still don't have a
clue on you know what they look like in
align:start position:0%
clue on you know what they look like in
align:start position:0%
clue on you know what they look like in
practice and all the sort of density
align:start position:0%
practice and all the sort of density
align:start position:0%
practice and all the sort of density
functional application go through a
align:start position:0%
functional application go through a
align:start position:0%
functional application go through a
procedure that will see later round that
align:start position:0%
procedure that will see later round that
align:start position:0%
procedure that will see later round that
is the sort of connection mapping that
align:start position:0%
is the sort of connection mapping that
align:start position:0%
is the sort of connection mapping that
gives a hint of what these objects look
align:start position:0%
gives a hint of what these objects look
align:start position:0%
gives a hint of what these objects look
like but up to now we are going to
align:start position:0%
like but up to now we are going to
align:start position:0%
like but up to now we are going to
introduce objects that are well defined
align:start position:0%
introduce objects that are well defined
align:start position:0%
introduce objects that are well defined
in principle but we don't know how they
align:start position:0%
in principle but we don't know how they
align:start position:0%
in principle but we don't know how they
look like and so that's right somehow
align:start position:0%
look like and so that's right somehow
align:start position:0%
look like and so that's right somehow
density functional theory is a much less
align:start position:0%
density functional theory is a much less
align:start position:0%
density functional theory is a much less
intuitive theory than something like
align:start position:0%
intuitive theory than something like
align:start position:0%
intuitive theory than something like
hartree-fock ok so this is going to work
align:start position:0%
hartree-fock ok so this is going to work
align:start position:0%
hartree-fock ok so this is going to work
the second hohenberg and confirm
align:start position:0%
the second hohenberg and confirm
align:start position:0%
the second hohenberg and confirm
defining the fundamental equation for
align:start position:0%
defining the fundamental equation for
align:start position:0%
defining the fundamental equation for
the charge density and this is the step
align:start position:0%
the charge density and this is the step
align:start position:0%
the charge density and this is the step
for any charge density Rho so someone
align:start position:0%
for any charge density Rho so someone
align:start position:0%
for any charge density Rho so someone
gives you someone draws you an arbitrary
align:start position:0%
gives you someone draws you an arbitrary
align:start position:0%
gives you someone draws you an arbitrary
charge density well we know that there
align:start position:0%
charge density well we know that there
align:start position:0%
charge density well we know that there
is an external potential of which that
align:start position:0%
is an external potential of which that
align:start position:0%
is an external potential of which that
charge density is the ground state we
align:start position:0%
charge density is the ground state we
align:start position:0%
charge density is the ground state we
don't know what it is honestly but we
align:start position:0%
don't know what it is honestly but we
align:start position:0%
don't know what it is honestly but we
have proven that there is a unique
align:start position:0%
have proven that there is a unique
align:start position:0%
have proven that there is a unique
external potential ok so because there
align:start position:0%
external potential ok so because there
align:start position:0%
external potential ok so because there
is a unique external potential the
align:start position:0%
is a unique external potential the
align:start position:0%
is a unique external potential the
reason am anybody's reading a question
align:start position:0%
reason am anybody's reading a question
align:start position:0%
reason am anybody's reading a question
with that potential in there and there
align:start position:0%
with that potential in there and there
align:start position:0%
with that potential in there and there
is a wave function that is going to be
align:start position:0%
is a wave function that is going to be
align:start position:0%
is a wave function that is going to be
the ground state wave function of that
align:start position:0%
the ground state wave function of that
align:start position:0%
the ground state wave function of that
many bodies Schrodinger equation so
align:start position:0%
many bodies Schrodinger equation so
align:start position:0%
many bodies Schrodinger equation so
given a certain raw we know that an
align:start position:0%
given a certain raw we know that an
align:start position:0%
given a certain raw we know that an
external potential exists and it's
align:start position:0%
external potential exists and it's
align:start position:0%
external potential exists and it's
unique in the terms it determines a
align:start position:0%
unique in the terms it determines a
align:start position:0%
unique in the terms it determines a
Schrodinger equation and that
align:start position:0%
Schrodinger equation and that
align:start position:0%
Schrodinger equation and that
Schrodinger equation that Germans a
align:start position:0%
Schrodinger equation that Germans a
align:start position:0%
Schrodinger equation that Germans a
ground state wave function that we call
align:start position:0%
ground state wave function that we call
align:start position:0%
ground state wave function that we call
sign so what we are saying is that given
align:start position:0%
sign so what we are saying is that given
align:start position:0%
sign so what we are saying is that given
a row in principle that sigh the ground
align:start position:0%
a row in principle that sigh the ground
align:start position:0%
a row in principle that sigh the ground
state wave function of the Schrodinger
align:start position:0%
state wave function of the Schrodinger
align:start position:0%
state wave function of the Schrodinger
equation in the external potential that
align:start position:0%
equation in the external potential that
align:start position:0%
equation in the external potential that
is uniquely defined by the row is also a
align:start position:0%
is uniquely defined by the row is also a
align:start position:0%
is uniquely defined by the row is also a
well-defined object again we don't know
align:start position:0%
well-defined object again we don't know
align:start position:0%
well-defined object again we don't know
what it is but it is well-defined and
align:start position:0%
what it is but it is well-defined and
align:start position:0%
what it is but it is well-defined and
because it's a well-defined object we
align:start position:0%
because it's a well-defined object we
align:start position:0%
because it's a well-defined object we
can calculate the expectation value of
align:start position:0%
can calculate the expectation value of
align:start position:0%
can calculate the expectation value of
that well define object of the quantum
align:start position:0%
that well define object of the quantum
align:start position:0%
that well define object of the quantum
kinetic energy you know minus 1/2 sum
align:start position:0%
kinetic energy you know minus 1/2 sum
align:start position:0%
kinetic energy you know minus 1/2 sum
over all I of the second derivatives and
align:start position:0%
over all I of the second derivatives and
align:start position:0%
over all I of the second derivatives and
the electron-electron interaction just
align:start position:0%
the electron-electron interaction just
align:start position:0%
the electron-electron interaction just
the 1 over RI minus RJ term so again
align:start position:0%
the 1 over RI minus RJ term so again
align:start position:0%
the 1 over RI minus RJ term so again
this term is in principle
align:start position:0%
this term is in principle
align:start position:0%
this term is in principle
well-defined and we call this term the
align:start position:0%
well-defined and we call this term the
align:start position:0%
well-defined and we call this term the
universal density functional the T's for
align:start position:0%
universal density functional the T's for
align:start position:0%
universal density functional the T's for
any given arbitrary Rho I
align:start position:0%
any given arbitrary Rho I
align:start position:0%
any given arbitrary Rho I
in principle can define a number that is
align:start position:0%
in principle can define a number that is
align:start position:0%
in principle can define a number that is
this number here is the Rho in principle
align:start position:0%
this number here is the Rho in principle
align:start position:0%
this number here is the Rho in principle
from the row I have the external
align:start position:0%
from the row I have the external
align:start position:0%
from the row I have the external
potential from the external potential I
align:start position:0%
potential from the external potential I
align:start position:0%
potential from the external potential I
have the Schrodinger equation in
align:start position:0%
have the Schrodinger equation in
align:start position:0%
have the Schrodinger equation in
principle I'm able to solve that
align:start position:0%
principle I'm able to solve that
align:start position:0%
principle I'm able to solve that
shreddin equation found in principle the
align:start position:0%
shreddin equation found in principle the
align:start position:0%
shreddin equation found in principle the
many-body ground state wave function
align:start position:0%
many-body ground state wave function
align:start position:0%
many-body ground state wave function
that will be precise and I can calculate
align:start position:0%
that will be precise and I can calculate
align:start position:0%
that will be precise and I can calculate
the expectation value of Phi of the
align:start position:0%
the expectation value of Phi of the
align:start position:0%
the expectation value of Phi of the
quantum kinetic energy and of the
align:start position:0%
quantum kinetic energy and of the
align:start position:0%
quantum kinetic energy and of the
electron-electron interaction term all
align:start position:0%
electron-electron interaction term all
align:start position:0%
electron-electron interaction term all
well defined we have really no clue on
align:start position:0%
well defined we have really no clue on
align:start position:0%
well defined we have really no clue on
how to calculate because we can't really
align:start position:0%
how to calculate because we can't really
align:start position:0%
how to calculate because we can't really
do in practice any of the steps but this
align:start position:0%
do in practice any of the steps but this
align:start position:0%
do in practice any of the steps but this
universal functional of the density is
align:start position:0%
universal functional of the density is
align:start position:0%
universal functional of the density is
well-defined
align:start position:0%
well-defined
align:start position:0%
well-defined
so with this universal functional that
align:start position:0%
so with this universal functional that
align:start position:0%
so with this universal functional that
is now well defined
align:start position:0%
is now well defined
align:start position:0%
is now well defined
we can write out something
align:start position:0%
we can write out something
align:start position:0%
we can write out something
we can write an
align:start position:0%
we can write an
align:start position:0%
we can write an
energy
align:start position:0%
energy
align:start position:0%
energy
for any given external potential and for
align:start position:0%
for any given external potential and for
align:start position:0%
for any given external potential and for
any given charge density and we write it
align:start position:0%
any given charge density and we write it
align:start position:0%
any given charge density and we write it
as this so for any given charge density
align:start position:0%
as this so for any given charge density
align:start position:0%
as this so for any given charge density
there will be a well-defined number that
align:start position:0%
there will be a well-defined number that
align:start position:0%
there will be a well-defined number that
is this universal density function of
align:start position:0%
is this universal density function of
align:start position:0%
is this universal density function of
data Rho Prime and then we add another
align:start position:0%
data Rho Prime and then we add another
align:start position:0%
data Rho Prime and then we add another
term that is just trivially the integral
align:start position:0%
term that is just trivially the integral
align:start position:0%
term that is just trivially the integral
of this V this external potential times
align:start position:0%
of this V this external potential times
align:start position:0%
of this V this external potential times
the charge density Rho prime so again
align:start position:0%
the charge density Rho prime so again
align:start position:0%
the charge density Rho prime so again
this new expression that we are written
align:start position:0%
this new expression that we are written
align:start position:0%
this new expression that we are written
is well defined for any Rho prime and
align:start position:0%
is well defined for any Rho prime and
align:start position:0%
is well defined for any Rho prime and
for any external potential we can
align:start position:0%
for any external potential we can
align:start position:0%
for any external potential we can
calculate trivially disturber and in
align:start position:0%
calculate trivially disturber and in
align:start position:0%
calculate trivially disturber and in
principle we know what this number is
align:start position:0%
principle we know what this number is
align:start position:0%
principle we know what this number is
and this is if you want
align:start position:0%
and this is if you want
align:start position:0%
and this is if you want
1964-1965
align:start position:0%
1964-1965
align:start position:0%
1964-1965
the reformulation of quantum mechanics
align:start position:0%
the reformulation of quantum mechanics
align:start position:0%
the reformulation of quantum mechanics
because now hohenberg and kona are able
align:start position:0%
because now hohenberg and kona are able
align:start position:0%
because now hohenberg and kona are able
to prove that there is a variational
align:start position:0%
to prove that there is a variational
align:start position:0%
to prove that there is a variational
principle that is for this expression
align:start position:0%
principle that is for this expression
align:start position:0%
principle that is for this expression
written here for this function of Rho
align:start position:0%
written here for this function of Rho
align:start position:0%
written here for this function of Rho
prime we can prove that for any Rho
align:start position:0%
prime we can prove that for any Rho
align:start position:0%
prime we can prove that for any Rho
prime that we can throw in a the overall
align:start position:0%
prime that we can throw in a the overall
align:start position:0%
prime that we can throw in a the overall
numerical value of this expression is
align:start position:0%
numerical value of this expression is
align:start position:0%
numerical value of this expression is
always going to be either greater or
align:start position:0%
always going to be either greater or
align:start position:0%
always going to be either greater or
equal to the ground state charge to the
align:start position:0%
equal to the ground state charge to the
align:start position:0%
equal to the ground state charge to the
ground state energy that we would obtain
align:start position:0%
ground state energy that we would obtain
align:start position:0%
ground state energy that we would obtain
from the shading equation in the
align:start position:0%
from the shading equation in the
align:start position:0%
from the shading equation in the
presence of this external potential so
align:start position:0%
presence of this external potential so
align:start position:0%
presence of this external potential so
now we have a well defined
align:start position:0%
now we have a well defined
align:start position:0%
now we have a well defined
density functional so if you have an
align:start position:0%
density functional so if you have an
align:start position:0%
density functional so if you have an
external potential the Z over R of your
align:start position:0%
external potential the Z over R of your
align:start position:0%
external potential the Z over R of your
otama you can try out now not wave
align:start position:0%
otama you can try out now not wave
align:start position:0%
otama you can try out now not wave
functions that are very difficult but
align:start position:0%
functions that are very difficult but
align:start position:0%
functions that are very difficult but
you can try out charge density and the
align:start position:0%
you can try out charge density and the
align:start position:0%
you can try out charge density and the
charge density that you the lowest
align:start position:0%
charge density that you the lowest
align:start position:0%
charge density that you the lowest
expectation value the lowest value for
align:start position:0%
expectation value the lowest value for
align:start position:0%
expectation value the lowest value for
this functional will be the ground state
align:start position:0%
this functional will be the ground state
align:start position:0%
this functional will be the ground state
and charge density
align:start position:0%
align:start position:0%
small problem we have no clue what this
align:start position:0%
small problem we have no clue what this
align:start position:0%
small problem we have no clue what this
looks like as a function of Rho Prime
align:start position:0%
looks like as a function of Rho Prime
align:start position:0%
looks like as a function of Rho Prime
but if we knew we would ever a
align:start position:0%
but if we knew we would ever a
align:start position:0%
but if we knew we would ever a
wonderfully simple approach to quantum
align:start position:0%
wonderfully simple approach to quantum
align:start position:0%
wonderfully simple approach to quantum
mechanics now we don't need to deal with
align:start position:0%
mechanics now we don't need to deal with
align:start position:0%
mechanics now we don't need to deal with
the many body complexity we just
align:start position:0%
the many body complexity we just
align:start position:0%
the many body complexity we just
minimize this expression as a function
align:start position:0%
minimize this expression as a function
align:start position:0%
minimize this expression as a function
of Rho Prime and again it's sort of
align:start position:0%
of Rho Prime and again it's sort of
align:start position:0%
of Rho Prime and again it's sort of
fairly easy to prove this variational
align:start position:0%
fairly easy to prove this variational
align:start position:0%
fairly easy to prove this variational
principle but when it's ready to sit
align:start position:0%
principle but when it's ready to sit
align:start position:0%
principle but when it's ready to sit
I've given you some readings so you are
align:start position:0%
I've given you some readings so you are
align:start position:0%
I've given you some readings so you are
welcome if you are really interested in
align:start position:0%
welcome if you are really interested in
align:start position:0%
welcome if you are really interested in
this to go back and read the first row
align:start position:0%
this to go back and read the first row
align:start position:0%
this to go back and read the first row
invariant consider and read the second
align:start position:0%
invariant consider and read the second
align:start position:0%
invariant consider and read the second
hohenberg and confit Rama but in many
align:start position:0%
hohenberg and confit Rama but in many
align:start position:0%
hohenberg and confit Rama but in many
ways the the proof of this second
align:start position:0%
ways the the proof of this second
align:start position:0%
ways the the proof of this second
hohenberg and Cohen theorem can be done
align:start position:0%
hohenberg and Cohen theorem can be done
align:start position:0%
hohenberg and Cohen theorem can be done
again through the variational principle
align:start position:0%
again through the variational principle
align:start position:0%
again through the variational principle
that is you know if we have a certain
align:start position:0%
that is you know if we have a certain
align:start position:0%
that is you know if we have a certain
Rho prime well that again uniquely
align:start position:0%
Rho prime well that again uniquely
align:start position:0%
Rho prime well that again uniquely
determine the ground state wave function
align:start position:0%
determine the ground state wave function
align:start position:0%
determine the ground state wave function
Rho prime will determine an external
align:start position:0%
Rho prime will determine an external
align:start position:0%
Rho prime will determine an external
potential that in principle is different
align:start position:0%
potential that in principle is different
align:start position:0%
potential that in principle is different
from this but Rho prime will determine
align:start position:0%
from this but Rho prime will determine
align:start position:0%
from this but Rho prime will determine
an external potential and will determine
align:start position:0%
an external potential and will determine
align:start position:0%
an external potential and will determine
our wave function that is the solution
align:start position:0%
our wave function that is the solution
align:start position:0%
our wave function that is the solution
of the many-body shading equation and if
align:start position:0%
of the many-body shading equation and if
align:start position:0%
of the many-body shading equation and if
we take the expectation value of
align:start position:0%
we take the expectation value of
align:start position:0%
we take the expectation value of
ara a meltonian with this external
align:start position:0%
ara a meltonian with this external
align:start position:0%
ara a meltonian with this external
potential in this but evaluated on the
align:start position:0%
potential in this but evaluated on the
align:start position:0%
potential in this but evaluated on the
wave function of C prime that comes from
align:start position:0%
wave function of C prime that comes from
align:start position:0%
wave function of C prime that comes from
discharge density Rho prime well we can
align:start position:0%
discharge density Rho prime well we can
align:start position:0%
discharge density Rho prime well we can
show that this expectation value here is
align:start position:0%
show that this expectation value here is
align:start position:0%
show that this expectation value here is
just identical to this functional that I
align:start position:0%
just identical to this functional that I
align:start position:0%
just identical to this functional that I
just written and for the variational
align:start position:0%
just written and for the variational
align:start position:0%
just written and for the variational
principle then it needs to be greater or
align:start position:0%
principle then it needs to be greater or
align:start position:0%
principle then it needs to be greater or
equal than zero
align:start position:0%
equal than zero
align:start position:0%
equal than zero
I want sort of dwell into that and again
align:start position:0%
I want sort of dwell into that and again
align:start position:0%
I want sort of dwell into that and again
you can look at the set of detail
align:start position:0%
you can look at the set of detail
align:start position:0%
you can look at the set of detail
description in sort of some of the many
align:start position:0%
description in sort of some of the many
align:start position:0%
description in sort of some of the many
references that I've given or that I've
align:start position:0%
references that I've given or that I've
align:start position:0%
references that I've given or that I've
also posted on the website but what is
align:start position:0%
also posted on the website but what is
align:start position:0%
also posted on the website but what is
conceptually important is that we have a
align:start position:0%
conceptually important is that we have a
align:start position:0%
conceptually important is that we have a
new equation you okay so 1964-65
align:start position:0%
new equation you okay so 1964-65
align:start position:0%
new equation you okay so 1964-65
quantum mechanics turned around we don't
align:start position:0%
quantum mechanics turned around we don't
align:start position:0%
quantum mechanics turned around we don't
have to think at many-body wave
align:start position:0%
have to think at many-body wave
align:start position:0%
have to think at many-body wave
functions we can think just a charge
align:start position:0%
functions we can think just a charge
align:start position:0%
functions we can think just a charge
density and
align:start position:0%
density and
align:start position:0%
density and
all would be well
align:start position:0%
all would be well
align:start position:0%
all would be well
apart from this detail that we don't
align:start position:0%
apart from this detail that we don't
align:start position:0%
apart from this detail that we don't
know what that function of F of Rho is
align:start position:0%
know what that function of F of Rho is
align:start position:0%
know what that function of F of Rho is
and so we have a conceptual approach but
align:start position:0%
and so we have a conceptual approach but
align:start position:0%
and so we have a conceptual approach but
we don't have a practical approach to
align:start position:0%
we don't have a practical approach to
align:start position:0%
we don't have a practical approach to
solve the density functional formulation
align:start position:0%
solve the density functional formulation
align:start position:0%
solve the density functional formulation
of quantum mechanics and this is if you
align:start position:0%
of quantum mechanics and this is if you
align:start position:0%
of quantum mechanics and this is if you
want a true to this day we don't know
align:start position:0%
want a true to this day we don't know
align:start position:0%
want a true to this day we don't know
what is the exact form of f of Rho if we
align:start position:0%
what is the exact form of f of Rho if we
align:start position:0%
what is the exact form of f of Rho if we
knew it sort of you know most of our
align:start position:0%
knew it sort of you know most of our
align:start position:0%
knew it sort of you know most of our
sort of quantum mechanical computational
align:start position:0%
sort of quantum mechanical computational
align:start position:0%
sort of quantum mechanical computational
problems would be trivially solved
align:start position:0%
problems would be trivially solved
align:start position:0%
problems would be trivially solved
because solving that variational
align:start position:0%
because solving that variational
align:start position:0%
because solving that variational
principle in the charge density would be
align:start position:0%
principle in the charge density would be
align:start position:0%
principle in the charge density would be
most likely a trivial thing to do the
align:start position:0%
most likely a trivial thing to do the
align:start position:0%
most likely a trivial thing to do the
issue is that not only we don't know but
align:start position:0%
issue is that not only we don't know but
align:start position:0%
issue is that not only we don't know but
we have understood a lot of what that
align:start position:0%
we have understood a lot of what that
align:start position:0%
we have understood a lot of what that
exchange correlation of what data
align:start position:0%
exchange correlation of what data
align:start position:0%
exchange correlation of what data
Universal density functional is and
align:start position:0%
Universal density functional is and
align:start position:0%
Universal density functional is and
it's very complex okay so it's unlikely
align:start position:0%
it's very complex okay so it's unlikely
align:start position:0%
it's very complex okay so it's unlikely
that there is a sort of simple
align:start position:0%
that there is a sort of simple
align:start position:0%
that there is a sort of simple
analytical expression of it as a
align:start position:0%
analytical expression of it as a
align:start position:0%
analytical expression of it as a
function of the charge density only but
align:start position:0%
function of the charge density only but
align:start position:0%
function of the charge density only but
you know the other sort of great piece
align:start position:0%
you know the other sort of great piece
align:start position:0%
you know the other sort of great piece
of if you want quantum engineering by
align:start position:0%
of if you want quantum engineering by
align:start position:0%
of if you want quantum engineering by
Walter Connor was finding out a very
align:start position:0%
Walter Connor was finding out a very
align:start position:0%
Walter Connor was finding out a very
good approximation to that density
align:start position:0%
good approximation to that density
align:start position:0%
good approximation to that density
functional okay we don't know what the
align:start position:0%
functional okay we don't know what the
align:start position:0%
functional okay we don't know what the
exact one is but now what they are doing
align:start position:0%
exact one is but now what they are doing
align:start position:0%
exact one is but now what they are doing
is well finding out one that is going to
align:start position:0%
is well finding out one that is going to
align:start position:0%
is well finding out one that is going to
be very very closely similar to the
align:start position:0%
be very very closely similar to the
align:start position:0%
be very very closely similar to the
exact one and so they are going to throw
align:start position:0%
exact one and so they are going to throw
align:start position:0%
exact one and so they are going to throw
in some physical intuition to this
align:start position:0%
in some physical intuition to this
align:start position:0%
in some physical intuition to this
problem that up to now if you want has
align:start position:0%
problem that up to now if you want has
align:start position:0%
problem that up to now if you want has
been a mathematical problem
align:start position:0%
been a mathematical problem
align:start position:0%
been a mathematical problem
it's another layer of complexity in this
align:start position:0%
it's another layer of complexity in this
align:start position:0%
it's another layer of complexity in this
discussion so I hope I'm not losing you
align:start position:0%
discussion so I hope I'm not losing you
align:start position:0%
discussion so I hope I'm not losing you
but sort of water
align:start position:0%
but sort of water
align:start position:0%
but sort of water
Walter Condit I think here the young
align:start position:0%
Walter Condit I think here the young
align:start position:0%
Walter Condit I think here the young
postdoc arriving from Cambridge Lucia
align:start position:0%
postdoc arriving from Cambridge Lucia
align:start position:0%
postdoc arriving from Cambridge Lucia
had just done is a PhD in England and
align:start position:0%
had just done is a PhD in England and
align:start position:0%
had just done is a PhD in England and
came there and certif you know I told
align:start position:0%
came there and certif you know I told
align:start position:0%
came there and certif you know I told
him I have this new variational
align:start position:0%
him I have this new variational
align:start position:0%
him I have this new variational
principle let's see what we can do to
align:start position:0%
principle let's see what we can do to
align:start position:0%
principle let's see what we can do to
make it into a practical solution
align:start position:0%
make it into a practical solution
align:start position:0%
make it into a practical solution
think they were in smithereens in San
align:start position:0%
think they were in smithereens in San
align:start position:0%
think they were in smithereens in San
Diego probably at that time okay so this
align:start position:0%
Diego probably at that time okay so this
align:start position:0%
Diego probably at that time okay so this
is what they are going to do remember
align:start position:0%
is what they are going to do remember
align:start position:0%
is what they are going to do remember
sort of you know what is the problem we
align:start position:0%
sort of you know what is the problem we
align:start position:0%
sort of you know what is the problem we
need to figure out what is a reasonable
align:start position:0%
need to figure out what is a reasonable
align:start position:0%
need to figure out what is a reasonable
approximation to this functional here so
align:start position:0%
approximation to this functional here so
align:start position:0%
approximation to this functional here so
what they say is well suppose that
align:start position:0%
what they say is well suppose that
align:start position:0%
what they say is well suppose that
someone is given as a this charge
align:start position:0%
someone is given as a this charge
align:start position:0%
someone is given as a this charge
density so we need in principle to find
align:start position:0%
density so we need in principle to find
align:start position:0%
density so we need in principle to find
out what would be the many-body wave
align:start position:0%
out what would be the many-body wave
align:start position:0%
out what would be the many-body wave
function that is solution of this
align:start position:0%
function that is solution of this
align:start position:0%
function that is solution of this
external potential that corresponds to
align:start position:0%
external potential that corresponds to
align:start position:0%
external potential that corresponds to
this charge density
align:start position:0%
this charge density
align:start position:0%
this charge density
this is going to be very complex let's
align:start position:0%
this is going to be very complex let's
align:start position:0%
this is going to be very complex let's
invent them a
align:start position:0%
invent them a
align:start position:0%
invent them a
problem in which electrons do not
align:start position:0%
problem in which electrons do not
align:start position:0%
problem in which electrons do not
interact between each other okay so
align:start position:0%
interact between each other okay so
align:start position:0%
interact between each other okay so
electron so that's that's the sort of
align:start position:0%
electron so that's that's the sort of
align:start position:0%
electron so that's that's the sort of
you know main problem in the Schrodinger
align:start position:0%
you know main problem in the Schrodinger
align:start position:0%
you know main problem in the Schrodinger
equation that electrons interacting with
align:start position:0%
equation that electrons interacting with
align:start position:0%
equation that electrons interacting with
each other introduce the two body
align:start position:0%
each other introduce the two body
align:start position:0%
each other introduce the two body
electrostatic repulsion in the shading
align:start position:0%
electrostatic repulsion in the shading
align:start position:0%
electrostatic repulsion in the shading
an equation and that what makes it
align:start position:0%
an equation and that what makes it
align:start position:0%
an equation and that what makes it
difficult well what connection say is
align:start position:0%
difficult well what connection say is
align:start position:0%
difficult well what connection say is
let's for a moment suppose that there is
align:start position:0%
let's for a moment suppose that there is
align:start position:0%
let's for a moment suppose that there is
a system of electrons that don't
align:start position:0%
a system of electrons that don't
align:start position:0%
a system of electrons that don't
interact the only thing that those
align:start position:0%
interact the only thing that those
align:start position:0%
interact the only thing that those
so-called connection electrons fill is
align:start position:0%
so-called connection electrons fill is
align:start position:0%
so-called connection electrons fill is
the external potential okay so those
align:start position:0%
the external potential okay so those
align:start position:0%
the external potential okay so those
connection electron will solve will
align:start position:0%
connection electron will solve will
align:start position:0%
connection electron will solve will
satisfy a Schrodinger equation that is
align:start position:0%
satisfy a Schrodinger equation that is
align:start position:0%
satisfy a Schrodinger equation that is
much simpler because there is no
align:start position:0%
much simpler because there is no
align:start position:0%
much simpler because there is no
electron electron interaction those
align:start position:0%
electron electron interaction those
align:start position:0%
electron electron interaction those
connection electron the only thing that
align:start position:0%
connection electron the only thing that
align:start position:0%
connection electron the only thing that
they feel is a new potential and they
align:start position:0%
they feel is a new potential and they
align:start position:0%
they feel is a new potential and they
will have their own a quantum kinetic
align:start position:0%
will have their own a quantum kinetic
align:start position:0%
will have their own a quantum kinetic
energy so what they are saying is for
align:start position:0%
energy so what they are saying is for
align:start position:0%
energy so what they are saying is for
any given
align:start position:0%
any given
align:start position:0%
any given
charge density Rho okay there is going
align:start position:0%
charge density Rho okay there is going
align:start position:0%
charge density Rho okay there is going
to be
align:start position:0%
to be
align:start position:0%
to be
non interacting set of electrons who's a
align:start position:0%
non interacting set of electrons who's a
align:start position:0%
non interacting set of electrons who's a
ground Stata charge density is identical
align:start position:0%
ground Stata charge density is identical
align:start position:0%
ground Stata charge density is identical
to row okay so we have said you know if
align:start position:0%
to row okay so we have said you know if
align:start position:0%
to row okay so we have said you know if
we ever charge density Rho you can all
align:start position:0%
we ever charge density Rho you can all
align:start position:0%
we ever charge density Rho you can all
go through you know find out the
align:start position:0%
go through you know find out the
align:start position:0%
go through you know find out the
external potential that concerned
align:start position:0%
external potential that concerned
align:start position:0%
external potential that concerned
they're all the shooting an equation
align:start position:0%
they're all the shooting an equation
align:start position:0%
they're all the shooting an equation
them anybody interacting electrons
align:start position:0%
them anybody interacting electrons
align:start position:0%
them anybody interacting electrons
solution but now what we are going to
align:start position:0%
solution but now what we are going to
align:start position:0%
solution but now what we are going to
say is we can also think at a system of
align:start position:0%
say is we can also think at a system of
align:start position:0%
say is we can also think at a system of
non-interacting electrons and we wanted
align:start position:0%
non-interacting electrons and we wanted
align:start position:0%
non-interacting electrons and we wanted
those non-interacting electrons to fill
align:start position:0%
those non-interacting electrons to fill
align:start position:0%
those non-interacting electrons to fill
a potential that is such that their
align:start position:0%
a potential that is such that their
align:start position:0%
a potential that is such that their
ground state is going to give us a
align:start position:0%
ground state is going to give us a
align:start position:0%
ground state is going to give us a
charge density that is identical to the
align:start position:0%
charge density that is identical to the
align:start position:0%
charge density that is identical to the
charge density I am dealing with
align:start position:0%
charge density I am dealing with
align:start position:0%
charge density I am dealing with
okay and we call that external potential
align:start position:0%
okay and we call that external potential
align:start position:0%
okay and we call that external potential
the konchem potential okay so now for
align:start position:0%
the konchem potential okay so now for
align:start position:0%
the konchem potential okay so now for
a charge dance if you don't only have to
align:start position:0%
a charge dance if you don't only have to
align:start position:0%
a charge dance if you don't only have to
think at all the complexity that i've
align:start position:0%
think at all the complexity that i've
align:start position:0%
think at all the complexity that i've
discussed up to now but you have also to
align:start position:0%
discussed up to now but you have also to
align:start position:0%
discussed up to now but you have also to
think that for a charge density there is
align:start position:0%
think that for a charge density there is
align:start position:0%
think that for a charge density there is
going to be the set of conan sham
align:start position:0%
going to be the set of conan sham
align:start position:0%
going to be the set of conan sham
non-interacting electrons and there is
align:start position:0%
non-interacting electrons and there is
align:start position:0%
non-interacting electrons and there is
going to be
align:start position:0%
going to be
align:start position:0%
going to be
potential that is called the connection
align:start position:0%
potential that is called the connection
align:start position:0%
potential that is called the connection
potential that is such that the ground
align:start position:0%
potential that is such that the ground
align:start position:0%
potential that is such that the ground
state of the shredding an equation for
align:start position:0%
state of the shredding an equation for
align:start position:0%
state of the shredding an equation for
non interacting electron that is without
align:start position:0%
non interacting electron that is without
align:start position:0%
non interacting electron that is without
the electron-electron interaction in
align:start position:0%
the electron-electron interaction in
align:start position:0%
the electron-electron interaction in
that connection potential will give us a
align:start position:0%
that connection potential will give us a
align:start position:0%
that connection potential will give us a
wave function and a ground data that is
align:start position:0%
wave function and a ground data that is
align:start position:0%
wave function and a ground data that is
that leads to a charge density identical
align:start position:0%
that leads to a charge density identical
align:start position:0%
that leads to a charge density identical
to the charge density and sort of
align:start position:0%
to the charge density and sort of
align:start position:0%
to the charge density and sort of
dealing with
align:start position:0%
dealing with
align:start position:0%
dealing with
okay what do we do with this well at
align:start position:0%
okay what do we do with this well at
align:start position:0%
okay what do we do with this well at
this stage
align:start position:0%
this stage
align:start position:0%
this stage
there is a sort of you know great
align:start position:0%
there is a sort of you know great
align:start position:0%
there is a sort of you know great
simplification that
align:start position:0%
simplification that
align:start position:0%
simplification that
for the Schrodinger equation of non
align:start position:0%
for the Schrodinger equation of non
align:start position:0%
for the Schrodinger equation of non
interacting electron we actually know
align:start position:0%
interacting electron we actually know
align:start position:0%
interacting electron we actually know
what is the exact solution so it's
align:start position:0%
what is the exact solution so it's
align:start position:0%
what is the exact solution so it's
actually very simple to solve a
align:start position:0%
actually very simple to solve a
align:start position:0%
actually very simple to solve a
Schrodinger equation in which the
align:start position:0%
Schrodinger equation in which the
align:start position:0%
Schrodinger equation in which the
electrons do not interact because now
align:start position:0%
electrons do not interact because now
align:start position:0%
electrons do not interact because now
this later the term Ananta is actually
align:start position:0%
this later the term Ananta is actually
align:start position:0%
this later the term Ananta is actually
the exact solution so if you have a set
align:start position:0%
the exact solution so if you have a set
align:start position:0%
the exact solution so if you have a set
of non-interacting electrons you to have
align:start position:0%
of non-interacting electrons you to have
align:start position:0%
of non-interacting electrons you to have
the electron-electron terming that's
align:start position:0%
the electron-electron terming that's
align:start position:0%
the electron-electron terming that's
reading a question the Slater
align:start position:0%
reading a question the Slater
align:start position:0%
reading a question the Slater
determinant is not only a good
align:start position:0%
determinant is not only a good
align:start position:0%
determinant is not only a good
approximation but it's actually the
align:start position:0%
approximation but it's actually the
align:start position:0%
approximation but it's actually the
exact solution okay so for this
align:start position:0%
exact solution okay so for this
align:start position:0%
exact solution okay so for this
non-interacting set of lectrons we can
align:start position:0%
non-interacting set of lectrons we can
align:start position:0%
non-interacting set of lectrons we can
solve everything exactly and in
align:start position:0%
solve everything exactly and in
align:start position:0%
solve everything exactly and in
particular we can calculate say what is
align:start position:0%
particular we can calculate say what is
align:start position:0%
particular we can calculate say what is
the kinetic energy of the set of
align:start position:0%
the kinetic energy of the set of
align:start position:0%
the kinetic energy of the set of
non-interacting electrons
align:start position:0%
non-interacting electrons
align:start position:0%
non-interacting electrons
okay so now we can set up you know F
align:start position:0%
okay so now we can set up you know F
align:start position:0%
okay so now we can set up you know F
somehow through the physical way of the
align:start position:0%
somehow through the physical way of the
align:start position:0%
somehow through the physical way of the
composer this mysterious dense
align:start position:0%
composer this mysterious dense
align:start position:0%
composer this mysterious dense
difunctional in two different terms okay
align:start position:0%
difunctional in two different terms okay
align:start position:0%
difunctional in two different terms okay
so what you're actually doing via the
align:start position:0%
so what you're actually doing via the
align:start position:0%
so what you're actually doing via the
connection mapping is
align:start position:0%
connection mapping is
align:start position:0%
connection mapping is
extracting from here terms that are very
align:start position:0%
extracting from here terms that are very
align:start position:0%
extracting from here terms that are very
large and that we know how to write we
align:start position:0%
large and that we know how to write we
align:start position:0%
large and that we know how to write we
know how to calculate and then sort of
align:start position:0%
know how to calculate and then sort of
align:start position:0%
know how to calculate and then sort of
you know hopefully we are going to
align:start position:0%
you know hopefully we are going to
align:start position:0%
you know hopefully we are going to
remain once we have extracted all these
align:start position:0%
remain once we have extracted all these
align:start position:0%
remain once we have extracted all these
terms that we know how to define we
align:start position:0%
terms that we know how to define we
align:start position:0%
terms that we know how to define we
remain with something that is very small
align:start position:0%
remain with something that is very small
align:start position:0%
remain with something that is very small
okay and that will find another
align:start position:0%
okay and that will find another
align:start position:0%
okay and that will find another
approximation numerical approximation
align:start position:0%
approximation numerical approximation
align:start position:0%
approximation numerical approximation
for it so connection say well we have
align:start position:0%
for it so connection say well we have
align:start position:0%
for it so connection say well we have
this well define density functional we
align:start position:0%
this well define density functional we
align:start position:0%
this well define density functional we
extract two terms that are well defined
align:start position:0%
extract two terms that are well defined
align:start position:0%
extract two terms that are well defined
and these two terms that sort of you
align:start position:0%
and these two terms that sort of you
align:start position:0%
and these two terms that sort of you
know the great achievement actually
align:start position:0%
know the great achievement actually
align:start position:0%
know the great achievement actually
contain most of the physics of our
align:start position:0%
contain most of the physics of our
align:start position:0%
contain most of the physics of our
problem and the sort of small term that
align:start position:0%
problem and the sort of small term that
align:start position:0%
problem and the sort of small term that
is left over we are going to approximate
align:start position:0%
is left over we are going to approximate
align:start position:0%
is left over we are going to approximate
in some simple way and that really the
align:start position:0%
in some simple way and that really the
align:start position:0%
in some simple way and that really the
approximation that they found worked
align:start position:0%
approximation that they found worked
align:start position:0%
approximation that they found worked
very well and that's one sort of density
align:start position:0%
very well and that's one sort of density
align:start position:0%
very well and that's one sort of density
functions really became a practical
align:start position:0%
functions really became a practical
align:start position:0%
functions really became a practical
theory and so in this sort of
align:start position:0%
theory and so in this sort of
align:start position:0%
theory and so in this sort of
density functional the first physical
align:start position:0%
density functional the first physical
align:start position:0%
density functional the first physical
large term that they extract is the
align:start position:0%
large term that they extract is the
align:start position:0%
large term that they extract is the
quantum kinetic energy that we call the
align:start position:0%
quantum kinetic energy that we call the
align:start position:0%
quantum kinetic energy that we call the
s naught of the real system because
align:start position:0%
s naught of the real system because
align:start position:0%
s naught of the real system because
again even if it's well defined we don't
align:start position:0%
again even if it's well defined we don't
align:start position:0%
again even if it's well defined we don't
know how to do that but what they were
align:start position:0%
know how to do that but what they were
align:start position:0%
know how to do that but what they were
able to write is the quantum kinetic
align:start position:0%
able to write is the quantum kinetic
align:start position:0%
able to write is the quantum kinetic
energy of this
align:start position:0%
energy of this
align:start position:0%
energy of this
knowning Dhingra problem so for a given
align:start position:0%
knowning Dhingra problem so for a given
align:start position:0%
knowning Dhingra problem so for a given
charge density there is this set of
align:start position:0%
charge density there is this set of
align:start position:0%
charge density there is this set of
connection non-interacting electrons
align:start position:0%
connection non-interacting electrons
align:start position:0%
connection non-interacting electrons
that lives in a potential such that they
align:start position:0%
that lives in a potential such that they
align:start position:0%
that lives in a potential such that they
have the same ground state charge
align:start position:0%
have the same ground state charge
align:start position:0%
have the same ground state charge
density and their kinetic energy is
align:start position:0%
density and their kinetic energy is
align:start position:0%
density and their kinetic energy is
trivial because it's going to be just
align:start position:0%
trivial because it's going to be just
align:start position:0%
trivial because it's going to be just
the kinetic energy of the Slater
align:start position:0%
the kinetic energy of the Slater
align:start position:0%
the kinetic energy of the Slater
determinant just a sum of single
align:start position:0%
determinant just a sum of single
align:start position:0%
determinant just a sum of single
particle term so for a charge density
align:start position:0%
particle term so for a charge density
align:start position:0%
particle term so for a charge density
now there is a well-defined quantum
align:start position:0%
now there is a well-defined quantum
align:start position:0%
now there is a well-defined quantum
kinetic energy that is not the true
align:start position:0%
kinetic energy that is not the true
align:start position:0%
kinetic energy that is not the true
point on kinetic energy of the system
align:start position:0%
point on kinetic energy of the system
align:start position:0%
point on kinetic energy of the system
but is the quantum kinetic energy of
align:start position:0%
but is the quantum kinetic energy of
align:start position:0%
but is the quantum kinetic energy of
this sort of
align:start position:0%
this sort of
align:start position:0%
this sort of
associated system of non-interacting
align:start position:0%
associated system of non-interacting
align:start position:0%
associated system of non-interacting
electrons but this term is now
align:start position:0%
electrons but this term is now
align:start position:0%
electrons but this term is now
well-defined they say well let's extract
align:start position:0%
well-defined they say well let's extract
align:start position:0%
well-defined they say well let's extract
another term that is well defined that
align:start position:0%
another term that is well defined that
align:start position:0%
another term that is well defined that
is just a hearty electrostatic energy of
align:start position:0%
is just a hearty electrostatic energy of
align:start position:0%
is just a hearty electrostatic energy of
a charge density distribution okay so if
align:start position:0%
a charge density distribution okay so if
align:start position:0%
a charge density distribution okay so if
we look at a charge density distribution
align:start position:0%
we look at a charge density distribution
align:start position:0%
we look at a charge density distribution
in which each infinitesimal volume
align:start position:0%
in which each infinitesimal volume
align:start position:0%
in which each infinitesimal volume
interacts with each other infinitesimal
align:start position:0%
interacts with each other infinitesimal
align:start position:0%
interacts with each other infinitesimal
volume with an electrostatic interaction
align:start position:0%
volume with an electrostatic interaction
align:start position:0%
volume with an electrostatic interaction
that's going to be the term and you know
align:start position:0%
that's going to be the term and you know
align:start position:0%
that's going to be the term and you know
what we are laughter is now something
align:start position:0%
what we are laughter is now something
align:start position:0%
what we are laughter is now something
that they call them the exchange
align:start position:0%
that they call them the exchange
align:start position:0%
that they call them the exchange
correlation term that is everything else
align:start position:0%
correlation term that is everything else
align:start position:0%
correlation term that is everything else
okay so f in principle is an exact
align:start position:0%
okay so f in principle is an exact
align:start position:0%
okay so f in principle is an exact
quantity we are now able to define a
align:start position:0%
quantity we are now able to define a
align:start position:0%
quantity we are now able to define a
quantum kinetic energy term that is an
align:start position:0%
quantum kinetic energy term that is an
align:start position:0%
quantum kinetic energy term that is an
exact quantity but it is not really the
align:start position:0%
exact quantity but it is not really the
align:start position:0%
exact quantity but it is not really the
quantum kinetic energy of the true
align:start position:0%
quantum kinetic energy of the true
align:start position:0%
quantum kinetic energy of the true
system but we sort of say you know this
align:start position:0%
system but we sort of say you know this
align:start position:0%
system but we sort of say you know this
is going to be equal to a well-defined
align:start position:0%
is going to be equal to a well-defined
align:start position:0%
is going to be equal to a well-defined
term plus another well-defined term plus
align:start position:0%
term plus another well-defined term plus
align:start position:0%
term plus another well-defined term plus
a third term that we don't know so we
align:start position:0%
a third term that we don't know so we
align:start position:0%
a third term that we don't know so we
have sort of decompose the quantity that
align:start position:0%
have sort of decompose the quantity that
align:start position:0%
have sort of decompose the quantity that
we have no clue on what it is into three
align:start position:0%
we have no clue on what it is into three
align:start position:0%
we have no clue on what it is into three
terms of which two terms are
align:start position:0%
terms of which two terms are
align:start position:0%
terms of which two terms are
well-defined and all our cluelessness is
align:start position:0%
well-defined and all our cluelessness is
align:start position:0%
well-defined and all our cluelessness is
contained in the third term and we call
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contained in the third term and we call
align:start position:0%
contained in the third term and we call
this third term the exchange correlation
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this third term the exchange correlation
align:start position:0%
this third term the exchange correlation
but the sort of physical advantage of
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but the sort of physical advantage of
align:start position:0%
but the sort of physical advantage of
having done this is that it turns out
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having done this is that it turns out
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having done this is that it turns out
that these two terms capture a lot of
align:start position:0%
that these two terms capture a lot of
align:start position:0%
that these two terms capture a lot of
the complexity of your problem and this
align:start position:0%
the complexity of your problem and this
align:start position:0%
the complexity of your problem and this
term
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term
align:start position:0%
term
tends to be fairly small okay so that's
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tends to be fairly small okay so that's
align:start position:0%
tends to be fairly small okay so that's
a that that's all actually that's why it
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a that that's all actually that's why it
align:start position:0%
a that that's all actually that's why it
was very well because somehow they
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was very well because somehow they
align:start position:0%
was very well because somehow they
managed to capture the complexity of our
align:start position:0%
managed to capture the complexity of our
align:start position:0%
managed to capture the complexity of our
system and so
align:start position:0%
align:start position:0%
once that exchange correlation term is
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once that exchange correlation term is
align:start position:0%
once that exchange correlation term is
defined and it's approximated in some
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defined and it's approximated in some
align:start position:0%
defined and it's approximated in some
way that we'll see in a moment our
align:start position:0%
way that we'll see in a moment our
align:start position:0%
way that we'll see in a moment our
problem is now well-defined because we
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problem is now well-defined because we
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problem is now well-defined because we
really have a variational principle
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really have a variational principle
align:start position:0%
really have a variational principle
remember the universal density
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remember the universal density
align:start position:0%
remember the universal density
functional class the external potential
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functional class the external potential
align:start position:0%
functional class the external potential
plus the charge density in the field of
align:start position:0%
plus the charge density in the field of
align:start position:0%
plus the charge density in the field of
the external potential
align:start position:0%
the external potential
align:start position:0%
the external potential
minimizes the sort of new variational
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minimizes the sort of new variational
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minimizes the sort of new variational
principle that comes from the hohenberg
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principle that comes from the hohenberg
align:start position:0%
principle that comes from the hohenberg
and confusion and so we can write it a
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and confusion and so we can write it a
align:start position:0%
and confusion and so we can write it a
variational principle that is this
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variational principle that is this
align:start position:0%
variational principle that is this
quantity
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quantity
align:start position:0%
quantity
with the constraint that the number of
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with the constraint that the number of
align:start position:0%
with the constraint that the number of
electrons should be equal to n ax should
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electrons should be equal to n ax should
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electrons should be equal to n ax should
be minimum and as usual when you sort of
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be minimum and as usual when you sort of
align:start position:0%
be minimum and as usual when you sort of
you know you write a variational
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you know you write a variational
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you know you write a variational
principle you are saying that sort of
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principle you are saying that sort of
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principle you are saying that sort of
you know the differential of that
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you know the differential of that
align:start position:0%
you know the differential of that
quantity needs to be equal to zero or if
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quantity needs to be equal to zero or if
align:start position:0%
quantity needs to be equal to zero or if
you want I mean this is a generic term
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you want I mean this is a generic term
align:start position:0%
you want I mean this is a generic term
you have a set of what are called Euler
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you have a set of what are called Euler
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you have a set of what are called Euler
Lagrange equation basically but it's
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Lagrange equation basically but it's
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Lagrange equation basically but it's
nothing else than differential analysis
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nothing else than differential analysis
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nothing else than differential analysis
that is you're asking yourself what are
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that is you're asking yourself what are
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that is you're asking yourself what are
going to be the conditions that need to
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going to be the conditions that need to
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going to be the conditions that need to
be satisfied by the charge density in
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be satisfied by the charge density in
align:start position:0%
be satisfied by the charge density in
order to satisfy the variational
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order to satisfy the variational
align:start position:0%
order to satisfy the variational
principle there is always this sort of
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principle there is always this sort of
align:start position:0%
principle there is always this sort of
one-to-one correspondence you have a
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one-to-one correspondence you have a
align:start position:0%
one-to-one correspondence you have a
variational principle it gives you
align:start position:0%
variational principle it gives you
align:start position:0%
variational principle it gives you
differential equation or you have
align:start position:0%
differential equation or you have
align:start position:0%
differential equation or you have
differential equation you can rewrite
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differential equation you can rewrite
align:start position:0%
differential equation you can rewrite
them in a variational principle we have
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them in a variational principle we have
align:start position:0%
them in a variational principle we have
seen that for the Schrodinger equation
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seen that for the Schrodinger equation
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seen that for the Schrodinger equation
and we see this in particular now in
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and we see this in particular now in
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and we see this in particular now in
explicitly for the
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explicitly for the
align:start position:0%
explicitly for the
connection orbitals so I'll actually go
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connection orbitals so I'll actually go
align:start position:0%
connection orbitals so I'll actually go
directly to the explicit expression of
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directly to the explicit expression of
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directly to the explicit expression of
the connection
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the connection
align:start position:0%
the connection
orbitals again remember that what we
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orbitals again remember that what we
align:start position:0%
orbitals again remember that what we
have done is we have defined a
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have done is we have defined a
align:start position:0%
have done is we have defined a
variational principle that acts on a
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variational principle that acts on a
align:start position:0%
variational principle that acts on a
universal density functional f plus the
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universal density functional f plus the
align:start position:0%
universal density functional f plus the
charge density and external potential
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charge density and external potential
align:start position:0%
charge density and external potential
and we have decomposed that we have
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and we have decomposed that we have
align:start position:0%
and we have decomposed that we have
extracted from this Universal functional
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extracted from this Universal functional
align:start position:0%
extracted from this Universal functional
sort of terms that are large and
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sort of terms that are large and
align:start position:0%
sort of terms that are large and
physical and we have sort of pushed all
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physical and we have sort of pushed all
align:start position:0%
physical and we have sort of pushed all
the many body complexity of the problem
align:start position:0%
the many body complexity of the problem
align:start position:0%
the many body complexity of the problem
in something that we call the exchange
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in something that we call the exchange
align:start position:0%
in something that we call the exchange
correlation functional that is again a
align:start position:0%
correlation functional that is again a
align:start position:0%
correlation functional that is again a
functional of the charge density we
align:start position:0%
functional of the charge density we
align:start position:0%
functional of the charge density we
don't know yet what that function of the
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don't know yet what that function of the
align:start position:0%
don't know yet what that function of the
charge density is but luckily it's going
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charge density is but luckily it's going
align:start position:0%
charge density is but luckily it's going
to be small so in a moment we'll
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to be small so in a moment we'll
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to be small so in a moment we'll
approximate it and then we ask ourselves
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approximate it and then we ask ourselves
align:start position:0%
approximate it and then we ask ourselves
what are the
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what are the
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what are the
variational what are the differential
align:start position:0%
variational what are the differential
align:start position:0%
variational what are the differential
equation that derive from this
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equation that derive from this
align:start position:0%
equation that derive from this
variational principle well in principle
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variational principle well in principle
align:start position:0%
variational principle well in principle
I had written them here okay we just
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I had written them here okay we just
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I had written them here okay we just
need to take the variation with respect
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need to take the variation with respect
align:start position:0%
need to take the variation with respect
to the charge density and imposing the
align:start position:0%
to the charge density and imposing the
align:start position:0%
to the charge density and imposing the
lagrange multiplication constraint and
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lagrange multiplication constraint and
align:start position:0%
lagrange multiplication constraint and
so this this would be heat basically the
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so this this would be heat basically the
align:start position:0%
so this this would be heat basically the
case the charge density needs to satisfy
align:start position:0%
case the charge density needs to satisfy
align:start position:0%
case the charge density needs to satisfy
this set of equation the sort of
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this set of equation the sort of
align:start position:0%
this set of equation the sort of
functional derivative of this non
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functional derivative of this non
align:start position:0%
functional derivative of this non
interacting quantum kinetic energy plus
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interacting quantum kinetic energy plus
align:start position:0%
interacting quantum kinetic energy plus
a number of terms that really contain
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a number of terms that really contain
align:start position:0%
a number of terms that really contain
the external potential the Hart
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the external potential the Hart
align:start position:0%
the external potential the Hart
interaction and exchange correlation
align:start position:0%
interaction and exchange correlation
align:start position:0%
interaction and exchange correlation
need to be equal to the Lagrange
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need to be equal to the Lagrange
align:start position:0%
need to be equal to the Lagrange
multiplier that fixes the number the
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multiplier that fixes the number the
align:start position:0%
multiplier that fixes the number the
number of electrons
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number of electrons
align:start position:0%
number of electrons
we are not able to calculate this
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we are not able to calculate this
align:start position:0%
we are not able to calculate this
functional derivative because remember
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functional derivative because remember
align:start position:0%
functional derivative because remember
the quantum kinetic energy of the non
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the quantum kinetic energy of the non
align:start position:0%
the quantum kinetic energy of the non
interacting system is again written as a
align:start position:0%
interacting system is again written as a
align:start position:0%
interacting system is again written as a
Slater determinant and so there is sort
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Slater determinant and so there is sort
align:start position:0%
Slater determinant and so there is sort
of you know this step back in which even
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of you know this step back in which even
align:start position:0%
of you know this step back in which even
if we had written everything in terms of
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if we had written everything in terms of
align:start position:0%
if we had written everything in terms of
a charge density we are not able to
align:start position:0%
a charge density we are not able to
align:start position:0%
a charge density we are not able to
explicitly calculate even not only the
align:start position:0%
explicitly calculate even not only the
align:start position:0%
explicitly calculate even not only the
derivative of the true interacting
align:start position:0%
derivative of the true interacting
align:start position:0%
derivative of the true interacting
electrons kinetic energy with respect to
align:start position:0%
electrons kinetic energy with respect to
align:start position:0%
electrons kinetic energy with respect to
Rho but we are not even able to
align:start position:0%
Rho but we are not even able to
align:start position:0%
Rho but we are not even able to
calculate the functional derivative of
align:start position:0%
calculate the functional derivative of
align:start position:0%
calculate the functional derivative of
the non interacting kinetic energy with
align:start position:0%
the non interacting kinetic energy with
align:start position:0%
the non interacting kinetic energy with
respect to Rho but what we are able is
align:start position:0%
respect to Rho but what we are able is
align:start position:0%
respect to Rho but what we are able is
actually to calculate the derivative of
align:start position:0%
actually to calculate the derivative of
align:start position:0%
actually to calculate the derivative of
that non interacting kinetic energy with
align:start position:0%
that non interacting kinetic energy with
align:start position:0%
that non interacting kinetic energy with
respect
align:start position:0%
respect
align:start position:0%
respect
to the orbitals that describe the
align:start position:0%
to the orbitals that describe the
align:start position:0%
to the orbitals that describe the
connection
align:start position:0%
connection
align:start position:0%
connection
remember that you know this
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remember that you know this
align:start position:0%
remember that you know this
non-independent connection electrons
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non-independent connection electrons
align:start position:0%
non-independent connection electrons
have an exact solution that is a Slater
align:start position:0%
have an exact solution that is a Slater
align:start position:0%
have an exact solution that is a Slater
determinant and so we know they're
align:start position:0%
determinant and so we know they're
align:start position:0%
determinant and so we know they're
trivial many-body wave function is a
align:start position:0%
trivial many-body wave function is a
align:start position:0%
trivial many-body wave function is a
Slater determinant composed by single
align:start position:0%
Slater determinant composed by single
align:start position:0%
Slater determinant composed by single
particle orbitals and the functional
align:start position:0%
particle orbitals and the functional
align:start position:0%
particle orbitals and the functional
derivative of data in the independent
align:start position:0%
derivative of data in the independent
align:start position:0%
derivative of data in the independent
non-interacting electrons kinetic energy
align:start position:0%
non-interacting electrons kinetic energy
align:start position:0%
non-interacting electrons kinetic energy
with respect to the single particle
align:start position:0%
with respect to the single particle
align:start position:0%
with respect to the single particle
orbital is now trivial and is just minus
align:start position:0%
orbital is now trivial and is just minus
align:start position:0%
orbital is now trivial and is just minus
1/2 L square so at the end of all these
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1/2 L square so at the end of all these
align:start position:0%
1/2 L square so at the end of all these
sort of complex
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sort of complex
align:start position:0%
sort of complex
formulation what we are left with it's
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formulation what we are left with it's
align:start position:0%
formulation what we are left with it's
something very simple and probably
align:start position:0%
something very simple and probably
align:start position:0%
something very simple and probably
something you should focus your
align:start position:0%
something you should focus your
align:start position:0%
something you should focus your
attention from now on we have now a set
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attention from now on we have now a set
align:start position:0%
attention from now on we have now a set
of connection equation that are the
align:start position:0%
of connection equation that are the
align:start position:0%
of connection equation that are the
differential equation that the electrons
align:start position:0%
differential equation that the electrons
align:start position:0%
differential equation that the electrons
need to satisfy in order to satisfy the
align:start position:0%
need to satisfy in order to satisfy the
align:start position:0%
need to satisfy in order to satisfy the
variational principle with the caveat
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variational principle with the caveat
align:start position:0%
variational principle with the caveat
a-- that in this connection equation
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a-- that in this connection equation
align:start position:0%
a-- that in this connection equation
there is a Therma an exchange
align:start position:0%
there is a Therma an exchange
align:start position:0%
there is a Therma an exchange
correlation term that we still don't
align:start position:0%
correlation term that we still don't
align:start position:0%
correlation term that we still don't
know what it is it's at the formally
align:start position:0%
know what it is it's at the formally
align:start position:0%
know what it is it's at the formally
defined as the functional derivative of
align:start position:0%
defined as the functional derivative of
align:start position:0%
defined as the functional derivative of
the exchange correlation energy with
align:start position:0%
the exchange correlation energy with
align:start position:0%
the exchange correlation energy with
respect to the charge density but we
align:start position:0%
respect to the charge density but we
align:start position:0%
respect to the charge density but we
need to approximate somewhere and what
align:start position:0%
need to approximate somewhere and what
align:start position:0%
need to approximate somewhere and what
this equation described is not anymore
align:start position:0%
this equation described is not anymore
align:start position:0%
this equation described is not anymore
the true electrons in your system but
align:start position:0%
the true electrons in your system but
align:start position:0%
the true electrons in your system but
they describe these cousins of the true
align:start position:0%
they describe these cousins of the true
align:start position:0%
they describe these cousins of the true
electrons they describe this connection
align:start position:0%
electrons they describe this connection
align:start position:0%
electrons they describe this connection
non-interacting electrons that have
align:start position:0%
non-interacting electrons that have
align:start position:0%
non-interacting electrons that have
their own orbital sy i and that will
align:start position:0%
their own orbital sy i and that will
align:start position:0%
their own orbital sy i and that will
give us a ground state charge density
align:start position:0%
give us a ground state charge density
align:start position:0%
give us a ground state charge density
that if the exchange correlation
align:start position:0%
that if the exchange correlation
align:start position:0%
that if the exchange correlation
functional was exact would be not only
align:start position:0%
functional was exact would be not only
align:start position:0%
functional was exact would be not only
this is obviously the same ground state
align:start position:0%
this is obviously the same ground state
align:start position:0%
this is obviously the same ground state
energy of our interacting electron
align:start position:0%
energy of our interacting electron
align:start position:0%
energy of our interacting electron
system but it would be set of the exact
align:start position:0%
system but it would be set of the exact
align:start position:0%
system but it would be set of the exact
solution of the problem
align:start position:0%
solution of the problem
align:start position:0%
solution of the problem
ok so this equation looked a lot like a
align:start position:0%
ok so this equation looked a lot like a
align:start position:0%
ok so this equation looked a lot like a
Schrodinger equation they look a lot if
align:start position:0%
Schrodinger equation they look a lot if
align:start position:0%
Schrodinger equation they look a lot if
you want like the hartree-fock equation
align:start position:0%
you want like the hartree-fock equation
align:start position:0%
you want like the hartree-fock equation
that we had written before because what
align:start position:0%
that we had written before because what
align:start position:0%
that we had written before because what
we are saying is that
align:start position:0%
align:start position:0%
Kaneesha electron I feel a quantum
align:start position:0%
Kaneesha electron I feel a quantum
align:start position:0%
Kaneesha electron I feel a quantum
kinetic energy operator feels a hearty
align:start position:0%
kinetic energy operator feels a hearty
align:start position:0%
kinetic energy operator feels a hearty
operator feels the external potential
align:start position:0%
operator feels the external potential
align:start position:0%
operator feels the external potential
and then fills this sort of you know
align:start position:0%
and then fills this sort of you know
align:start position:0%
and then fills this sort of you know
remaining term that is the exchange
align:start position:0%
remaining term that is the exchange
align:start position:0%
remaining term that is the exchange
correlation potential again if we knew
align:start position:0%
correlation potential again if we knew
align:start position:0%
correlation potential again if we knew
what were this exact exchange
align:start position:0%
what were this exact exchange
align:start position:0%
what were this exact exchange
correlation potential we would have an
align:start position:0%
correlation potential we would have an
align:start position:0%
correlation potential we would have an
exact solution to the problem but we
align:start position:0%
exact solution to the problem but we
align:start position:0%
exact solution to the problem but we
know very good approximation and then if
align:start position:0%
know very good approximation and then if
align:start position:0%
know very good approximation and then if
you want find in the ground state is not
align:start position:0%
you want find in the ground state is not
align:start position:0%
you want find in the ground state is not
very different now finding the ground
align:start position:0%
very different now finding the ground
align:start position:0%
very different now finding the ground
state of the hartree-fock equation with
align:start position:0%
state of the hartree-fock equation with
align:start position:0%
state of the hartree-fock equation with
the caveat that actually this term here
align:start position:0%
the caveat that actually this term here
align:start position:0%
the caveat that actually this term here
is going to be much simpler than the
align:start position:0%
is going to be much simpler than the
align:start position:0%
is going to be much simpler than the
exchange term of the hartree-fock
align:start position:0%
exchange term of the hartree-fock
align:start position:0%
exchange term of the hartree-fock
equation if you go back to the first
align:start position:0%
equation if you go back to the first
align:start position:0%
equation if you go back to the first
slide to the hartree-fock equation the
align:start position:0%
slide to the hartree-fock equation the
align:start position:0%
slide to the hartree-fock equation the
last term is a
align:start position:0%
last term is a
align:start position:0%
last term is a
numerically very complex expression in
align:start position:0%
numerically very complex expression in
align:start position:0%
numerically very complex expression in
which we sort of take the orbital and we
align:start position:0%
which we sort of take the orbital and we
align:start position:0%
which we sort of take the orbital and we
put it inside
align:start position:0%
put it inside
align:start position:0%
put it inside
integral differential operator now it's
align:start position:0%
integral differential operator now it's
align:start position:0%
integral differential operator now it's
become simpler and that's all if you
align:start position:0%
become simpler and that's all if you
align:start position:0%
become simpler and that's all if you
want so the connection equation looks
align:start position:0%
want so the connection equation looks
align:start position:0%
want so the connection equation looks
very similar in practice they are
align:start position:0%
very similar in practice they are
align:start position:0%
very similar in practice they are
simpler to solver they tend to be more
align:start position:0%
simpler to solver they tend to be more
align:start position:0%
simpler to solver they tend to be more
accurate in most cases and that's at the
align:start position:0%
accurate in most cases and that's at the
align:start position:0%
accurate in most cases and that's at the
end what leads to the success but what
align:start position:0%
end what leads to the success but what
align:start position:0%
end what leads to the success but what
is critical for all of this is having a
align:start position:0%
is critical for all of this is having a
align:start position:0%
is critical for all of this is having a
reasonable approximation to the exchange
align:start position:0%
reasonable approximation to the exchange
align:start position:0%
reasonable approximation to the exchange
correlation potential if we add the
align:start position:0%
correlation potential if we add the
align:start position:0%
correlation potential if we add the
exact exchange correlation potential
align:start position:0%
exact exchange correlation potential
align:start position:0%
exact exchange correlation potential
everything would be exact in this
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everything would be exact in this
align:start position:0%
everything would be exact in this
formulation we would find a connection
align:start position:0%
formulation we would find a connection
align:start position:0%
formulation we would find a connection
independent electrons that we are sort
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independent electrons that we are sort
align:start position:0%
independent electrons that we are sort
of you know the ground state electrons
align:start position:0%
of you know the ground state electrons
align:start position:0%
of you know the ground state electrons
for that charge density that is
align:start position:0%
for that charge density that is
align:start position:0%
for that charge density that is
ultimately equal to the charge density
align:start position:0%
ultimately equal to the charge density
align:start position:0%
ultimately equal to the charge density
of the interacting electrons in this
align:start position:0%
of the interacting electrons in this
align:start position:0%
of the interacting electrons in this
external potential
align:start position:0%
align:start position:0%
ok and
align:start position:0%
align:start position:0%
we have the
align:start position:0%
we have the
align:start position:0%
we have the
Euler Lagrangian or connection
align:start position:0%
Euler Lagrangian or connection
align:start position:0%
Euler Lagrangian or connection
differential equation in the previous
align:start position:0%
differential equation in the previous
align:start position:0%
differential equation in the previous
page I written here and sort of you know
align:start position:0%
page I written here and sort of you know
align:start position:0%
page I written here and sort of you know
just for reference also what would be
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just for reference also what would be
align:start position:0%
just for reference also what would be
the total energy of the system and
align:start position:0%
the total energy of the system and
align:start position:0%
the total energy of the system and
usually if you had
align:start position:0%
usually if you had
align:start position:0%
usually if you had
independent electron the total energy of
align:start position:0%
independent electron the total energy of
align:start position:0%
independent electron the total energy of
the system is trivially the sum of each
align:start position:0%
the system is trivially the sum of each
align:start position:0%
the system is trivially the sum of each
of the single particle energies okay if
align:start position:0%
of the single particle energies okay if
align:start position:0%
of the single particle energies okay if
you have ten electrons and they don't
align:start position:0%
you have ten electrons and they don't
align:start position:0%
you have ten electrons and they don't
interact with each other you can
align:start position:0%
interact with each other you can
align:start position:0%
interact with each other you can
calculate what is the energy of each of
align:start position:0%
calculate what is the energy of each of
align:start position:0%
calculate what is the energy of each of
these ten electron sum all of them and
align:start position:0%
these ten electron sum all of them and
align:start position:0%
these ten electron sum all of them and
that's the total energy of the system in
align:start position:0%
that's the total energy of the system in
align:start position:0%
that's the total energy of the system in
this case it's it's it's more complex
align:start position:0%
this case it's it's it's more complex
align:start position:0%
this case it's it's it's more complex
and the total energy of the system can't
align:start position:0%
and the total energy of the system can't
align:start position:0%
and the total energy of the system can't
be really written as that but it's got
align:start position:0%
be really written as that but it's got
align:start position:0%
be really written as that but it's got
other terms that depend on the charge
align:start position:0%
other terms that depend on the charge
align:start position:0%
other terms that depend on the charge
density but sort of this is you know in
align:start position:0%
density but sort of this is you know in
align:start position:0%
density but sort of this is you know in
summary what your total energy is and
align:start position:0%
summary what your total energy is and
align:start position:0%
summary what your total energy is and
again is nothing else than kinetic
align:start position:0%
again is nothing else than kinetic
align:start position:0%
again is nothing else than kinetic
energy term sort of a heart return
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energy term sort of a heart return
align:start position:0%
energy term sort of a heart return
function of the charge density this
align:start position:0%
function of the charge density this
align:start position:0%
function of the charge density this
exchange correlation functional and the
align:start position:0%
exchange correlation functional and the
align:start position:0%
exchange correlation functional and the
interaction interaction between external
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interaction interaction between external
align:start position:0%
interaction interaction between external
potential and the charge density but
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potential and the charge density but
align:start position:0%
potential and the charge density but
this is actually different
align:start position:0%
align:start position:0%
from the sum of the eigenvalues that
align:start position:0%
from the sum of the eigenvalues that
align:start position:0%
from the sum of the eigenvalues that
would be the sum of the expectation
align:start position:0%
would be the sum of the expectation
align:start position:0%
would be the sum of the expectation
values of a I
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values of a I
align:start position:0%
values of a I
calculated
align:start position:0%
align:start position:0%
on the single particle orbital where T
align:start position:0%
on the single particle orbital where T
align:start position:0%
on the single particle orbital where T
is again just a simple quantum kinetic
align:start position:0%
is again just a simple quantum kinetic
align:start position:0%
is again just a simple quantum kinetic
energy and bks is this connection
align:start position:0%
energy and bks is this connection
align:start position:0%
energy and bks is this connection
potential so if you want to calculate
align:start position:0%
potential so if you want to calculate
align:start position:0%
potential so if you want to calculate
the total energy of your system even if
align:start position:0%
the total energy of your system even if
align:start position:0%
the total energy of your system even if
it made of independent electron you
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it made of independent electron you
align:start position:0%
it made of independent electron you
can't some just a single particle
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can't some just a single particle
align:start position:0%
can't some just a single particle
orbitals but you have to sort of deal
align:start position:0%
orbitals but you have to sort of deal
align:start position:0%
orbitals but you have to sort of deal
with this expression nothing complex in
align:start position:0%
with this expression nothing complex in
align:start position:0%
with this expression nothing complex in
this is that sort of a caveat that is
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this is that sort of a caveat that is
align:start position:0%
this is that sort of a caveat that is
relevant when you want to sort of you
align:start position:0%
relevant when you want to sort of you
align:start position:0%
relevant when you want to sort of you
know this is the reason why we can't
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know this is the reason why we can't
align:start position:0%
know this is the reason why we can't
really find out the equivalent of the
align:start position:0%
really find out the equivalent of the
align:start position:0%
really find out the equivalent of the
Koopman theorems for hartree-fock this
align:start position:0%
Koopman theorems for hartree-fock this
align:start position:0%
Koopman theorems for hartree-fock this
is why at the end there's a single
align:start position:0%
is why at the end there's a single
align:start position:0%
is why at the end there's a single
particle
align:start position:0%
particle
align:start position:0%
particle
energies are ultimately not physically
align:start position:0%
energies are ultimately not physically
align:start position:0%
energies are ultimately not physically
meaningful they're sort of you know done
align:start position:0%
meaningful they're sort of you know done
align:start position:0%
meaningful they're sort of you know done
gives us the total energy of the system
align:start position:0%
gives us the total energy of the system
align:start position:0%
gives us the total energy of the system
just by taking the sum over all of them
align:start position:0%
just by taking the sum over all of them
align:start position:0%
just by taking the sum over all of them
okay so in order to make this into a
align:start position:0%
okay so in order to make this into a
align:start position:0%
okay so in order to make this into a
practical algorithm the only part that
align:start position:0%
practical algorithm the only part that
align:start position:0%
practical algorithm the only part that
remains is finding an approximation to
align:start position:0%
remains is finding an approximation to
align:start position:0%
remains is finding an approximation to
that exchange correlation term to that
align:start position:0%
that exchange correlation term to that
align:start position:0%
that exchange correlation term to that
last term remember we had sort of
align:start position:0%
last term remember we had sort of
align:start position:0%
last term remember we had sort of
defined is the NC functional we have
align:start position:0%
defined is the NC functional we have
align:start position:0%
defined is the NC functional we have
been able to extract two meaningful
align:start position:0%
been able to extract two meaningful
align:start position:0%
been able to extract two meaningful
terms the Hartree
align:start position:0%
terms the Hartree
align:start position:0%
terms the Hartree
electrostatic energy and the non
align:start position:0%
electrostatic energy and the non
align:start position:0%
electrostatic energy and the non
interacting connection kinetic energy
align:start position:0%
interacting connection kinetic energy
align:start position:0%
interacting connection kinetic energy
and we have said what is left is a
align:start position:0%
and we have said what is left is a
align:start position:0%
and we have said what is left is a
function of the charge density that we
align:start position:0%
function of the charge density that we
align:start position:0%
function of the charge density that we
call the exchange correlation functional
align:start position:0%
call the exchange correlation functional
align:start position:0%
call the exchange correlation functional
how we are going to approximate data
align:start position:0%
how we are going to approximate data
align:start position:0%
how we are going to approximate data
well we go back to the thomas fermi idea
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well we go back to the thomas fermi idea
align:start position:0%
well we go back to the thomas fermi idea
we are going to do a local density
align:start position:0%
we are going to do a local density
align:start position:0%
we are going to do a local density
approximation to data exchange
align:start position:0%
approximation to data exchange
align:start position:0%
approximation to data exchange
correlation functional so again what we
align:start position:0%
correlation functional so again what we
align:start position:0%
correlation functional so again what we
want to calculate is the exchange
align:start position:0%
want to calculate is the exchange
align:start position:0%
want to calculate is the exchange
correlation energy for any arbitrary
align:start position:0%
correlation energy for any arbitrary
align:start position:0%
correlation energy for any arbitrary
charge density sometimes I call the
align:start position:0%
charge density sometimes I call the
align:start position:0%
charge density sometimes I call the
charge density and sometimes I call the
align:start position:0%
charge density and sometimes I call the
align:start position:0%
charge density and sometimes I call the
charge density Rho but they are always
align:start position:0%
charge density Rho but they are always
align:start position:0%
charge density Rho but they are always
the same so how do we do this well we
align:start position:0%
the same so how do we do this well we
align:start position:0%
the same so how do we do this well we
don't have the full solution but what we
align:start position:0%
don't have the full solution but what we
align:start position:0%
don't have the full solution but what we
can say again is that for a you know mo
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can say again is that for a you know mo
align:start position:0%
can say again is that for a you know mo
genius charge density that is you know
align:start position:0%
genius charge density that is you know
align:start position:0%
genius charge density that is you know
changes values and then drops to zero I
align:start position:0%
changes values and then drops to zero I
align:start position:0%
changes values and then drops to zero I
can calculate the exchange correlation
align:start position:0%
can calculate the exchange correlation
align:start position:0%
can calculate the exchange correlation
energy for this charge density
align:start position:0%
energy for this charge density
align:start position:0%
energy for this charge density
distribution
align:start position:0%
distribution
align:start position:0%
distribution
by sort of you know decomposing Gita in
align:start position:0%
by sort of you know decomposing Gita in
align:start position:0%
by sort of you know decomposing Gita in
infinitesimal volume
align:start position:0%
infinitesimal volume
align:start position:0%
infinitesimal volume
inside each infinitesimal volume I can
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inside each infinitesimal volume I can
align:start position:0%
inside each infinitesimal volume I can
say the charge density is constant and
align:start position:0%
say the charge density is constant and
align:start position:0%
say the charge density is constant and
you see I make a local dense the
align:start position:0%
you see I make a local dense the
align:start position:0%
you see I make a local dense the
approximation that is I say the
align:start position:0%
approximation that is I say the
align:start position:0%
approximation that is I say the
contribution to the overall
align:start position:0%
contribution to the overall
align:start position:0%
contribution to the overall
exchange correlation energy of this
align:start position:0%
exchange correlation energy of this
align:start position:0%
exchange correlation energy of this
non-homogeneous system can be broken
align:start position:0%
non-homogeneous system can be broken
align:start position:0%
non-homogeneous system can be broken
down and each infinitesimal volume will
align:start position:0%
down and each infinitesimal volume will
align:start position:0%
down and each infinitesimal volume will
give its own contribution to the total
align:start position:0%
give its own contribution to the total
align:start position:0%
give its own contribution to the total
exchange correlation density this is you
align:start position:0%
exchange correlation density this is you
align:start position:0%
exchange correlation density this is you
know in principle it's not correct I
align:start position:0%
know in principle it's not correct I
align:start position:0%
know in principle it's not correct I
mean our problem doesn't have to be
align:start position:0%
mean our problem doesn't have to be
align:start position:0%
mean our problem doesn't have to be
local in any way actually as people say
align:start position:0%
local in any way actually as people say
align:start position:0%
local in any way actually as people say
this exchange correlation functional the
align:start position:0%
this exchange correlation functional the
align:start position:0%
this exchange correlation functional the
true one although we don't know what it
align:start position:0%
true one although we don't know what it
align:start position:0%
true one although we don't know what it
is and we know that is ultra non-local
align:start position:0%
is and we know that is ultra non-local
align:start position:0%
is and we know that is ultra non-local
so it can't be decomposed into terms
align:start position:0%
so it can't be decomposed into terms
align:start position:0%
so it can't be decomposed into terms
that independently sum up so in
align:start position:0%
that independently sum up so in
align:start position:0%
that independently sum up so in
principle we can do this but in practice
align:start position:0%
principle we can do this but in practice
align:start position:0%
principle we can do this but in practice
it tends to be a good approximation for
align:start position:0%
it tends to be a good approximation for
align:start position:0%
it tends to be a good approximation for
a lot of cases and so what is going to
align:start position:0%
a lot of cases and so what is going to
align:start position:0%
a lot of cases and so what is going to
be the contribution to the exchange
align:start position:0%
be the contribution to the exchange
align:start position:0%
be the contribution to the exchange
correlation energy from this
align:start position:0%
correlation energy from this
align:start position:0%
correlation energy from this
infinitesimal volume where say the
align:start position:0%
infinitesimal volume where say the
align:start position:0%
infinitesimal volume where say the
charge density there is a 0.5 well what
align:start position:0%
charge density there is a 0.5 well what
align:start position:0%
charge density there is a 0.5 well what
we need to do is we need to find out
align:start position:0%
we need to do is we need to find out
align:start position:0%
we need to do is we need to find out
what is the exchange correlation energy
align:start position:0%
what is the exchange correlation energy
align:start position:0%
what is the exchange correlation energy
for the homogeneous electron gas that is
align:start position:0%
for the homogeneous electron gas that is
align:start position:0%
for the homogeneous electron gas that is
at this density that's something that
align:start position:0%
at this density that's something that
align:start position:0%
at this density that's something that
with some advanced computational
align:start position:0%
with some advanced computational
align:start position:0%
with some advanced computational
techniques we can actually find out
align:start position:0%
techniques we can actually find out
align:start position:0%
techniques we can actually find out
almost exactly so we would know if we
align:start position:0%
almost exactly so we would know if we
align:start position:0%
almost exactly so we would know if we
add a homogeneous charge density point 5
align:start position:0%
add a homogeneous charge density point 5
align:start position:0%
add a homogeneous charge density point 5
everywhere what would be the charge
align:start position:0%
everywhere what would be the charge
align:start position:0%
everywhere what would be the charge
density per unit volume and we can find
align:start position:0%
density per unit volume and we can find
align:start position:0%
density per unit volume and we can find
out what is you know the exchange
align:start position:0%
out what is you know the exchange
align:start position:0%
out what is you know the exchange
correlation charge density per unit
align:start position:0%
correlation charge density per unit
align:start position:0%
correlation charge density per unit
volume not only four point five point
align:start position:0%
volume not only four point five point
align:start position:0%
volume not only four point five point
six point seven any finger and what we
align:start position:0%
six point seven any finger and what we
align:start position:0%
six point seven any finger and what we
are saying is that in this
align:start position:0%
are saying is that in this
align:start position:0%
are saying is that in this
non-homogeneous problem we construct the
align:start position:0%
non-homogeneous problem we construct the
align:start position:0%
non-homogeneous problem we construct the
overall exchange correlation energy by
align:start position:0%
overall exchange correlation energy by
align:start position:0%
overall exchange correlation energy by
summing up these different pieces and so
align:start position:0%
summing up these different pieces and so
align:start position:0%
summing up these different pieces and so
this is what separately and other did in
align:start position:0%
this is what separately and other did in
align:start position:0%
this is what separately and other did in
1980 they basically found out
align:start position:0%
1980 they basically found out
align:start position:0%
1980 they basically found out
what was the
align:start position:0%
what was the
align:start position:0%
what was the
almost exact sort of closely to
align:start position:0%
almost exact sort of closely to
align:start position:0%
almost exact sort of closely to
numerical exact solution for the
align:start position:0%
numerical exact solution for the
align:start position:0%
numerical exact solution for the
homogeneous electron gas the Tisza for a
align:start position:0%
homogeneous electron gas the Tisza for a
align:start position:0%
homogeneous electron gas the Tisza for a
system in which you have only electrons
align:start position:0%
system in which you have only electrons
align:start position:0%
system in which you have only electrons
homogeneously so the charge density is
align:start position:0%
homogeneously so the charge density is
align:start position:0%
homogeneously so the charge density is
identical everywhere and those electron
align:start position:0%
identical everywhere and those electron
align:start position:0%
identical everywhere and those electron
interact so you can calculate the energy
align:start position:0%
interact so you can calculate the energy
align:start position:0%
interact so you can calculate the energy
of this interacting electron problem
align:start position:0%
of this interacting electron problem
align:start position:0%
of this interacting electron problem
exactly as a function of the density
align:start position:0%
exactly as a function of the density
align:start position:0%
exactly as a function of the density
okay so you change the density in your
align:start position:0%
okay so you change the density in your
align:start position:0%
okay so you change the density in your
sort of volume and you find out what is
align:start position:0%
sort of volume and you find out what is
align:start position:0%
sort of volume and you find out what is
this energy and then you can calculate
align:start position:0%
this energy and then you can calculate
align:start position:0%
this energy and then you can calculate
what is for you know any of these
align:start position:0%
what is for you know any of these
align:start position:0%
what is for you know any of these
density what is the
align:start position:0%
density what is the
align:start position:0%
density what is the
connection quantum kinetic energy you
align:start position:0%
connection quantum kinetic energy you
align:start position:0%
connection quantum kinetic energy you
can find out what is the Hartree
align:start position:0%
can find out what is the Hartree
align:start position:0%
can find out what is the Hartree
electrostatic energy and so you can also
align:start position:0%
electrostatic energy and so you can also
align:start position:0%
electrostatic energy and so you can also
find out for the specific case of the
align:start position:0%
find out for the specific case of the
align:start position:0%
find out for the specific case of the
homogeneous gas you can find out
align:start position:0%
homogeneous gas you can find out
align:start position:0%
homogeneous gas you can find out
numerically what would be the exchange
align:start position:0%
numerically what would be the exchange
align:start position:0%
numerically what would be the exchange
correlation density and so that's
align:start position:0%
correlation density and so that's
align:start position:0%
correlation density and so that's
basically a function so for the
align:start position:0%
basically a function so for the
align:start position:0%
basically a function so for the
homogeneous gas that is for the casing
align:start position:0%
homogeneous gas that is for the casing
align:start position:0%
homogeneous gas that is for the casing
which n doesn't depend on R people found
align:start position:0%
which n doesn't depend on R people found
align:start position:0%
which n doesn't depend on R people found
out what was basically these
align:start position:0%
out what was basically these
align:start position:0%
out what was basically these
exchange correlation energy it was
align:start position:0%
exchange correlation energy it was
align:start position:0%
exchange correlation energy it was
calculated
align:start position:0%
calculated
align:start position:0%
calculated
as a function this is a function
align:start position:0%
as a function this is a function
align:start position:0%
as a function this is a function
of what people call RS Araiza is the
align:start position:0%
of what people call RS Araiza is the
align:start position:0%
of what people call RS Araiza is the
radius of a sphere that contains one
align:start position:0%
radius of a sphere that contains one
align:start position:0%
radius of a sphere that contains one
electron so it sort of you know inverse
align:start position:0%
electron so it sort of you know inverse
align:start position:0%
electron so it sort of you know inverse
quantity with respect to the density so
align:start position:0%
quantity with respect to the density so
align:start position:0%
quantity with respect to the density so
numerical calculation what are called
align:start position:0%
numerical calculation what are called
align:start position:0%
numerical calculation what are called
quantum Monte Carlo calculation really
align:start position:0%
quantum Monte Carlo calculation really
align:start position:0%
quantum Monte Carlo calculation really
solved the interacting ash reading an
align:start position:0%
solved the interacting ash reading an
align:start position:0%
solved the interacting ash reading an
equation problem but for the specific
align:start position:0%
equation problem but for the specific
align:start position:0%
equation problem but for the specific
case of an electron gas that there's a
align:start position:0%
case of an electron gas that there's a
align:start position:0%
case of an electron gas that there's a
homogeneous density they were able to do
align:start position:0%
homogeneous density they were able to do
align:start position:0%
homogeneous density they were able to do
that for various density and so now we
align:start position:0%
that for various density and so now we
align:start position:0%
that for various density and so now we
have a function for the homogeneous
align:start position:0%
have a function for the homogeneous
align:start position:0%
have a function for the homogeneous
problem for the non-homogeneous problem
align:start position:0%
problem for the non-homogeneous problem
align:start position:0%
problem for the non-homogeneous problem
we take a local density approximation
align:start position:0%
we take a local density approximation
align:start position:0%
we take a local density approximation
and we say that the overall exchange
align:start position:0%
and we say that the overall exchange
align:start position:0%
and we say that the overall exchange
correlation energy is given by the
align:start position:0%
correlation energy is given by the
align:start position:0%
correlation energy is given by the
integral over all the infinitesimal
align:start position:0%
integral over all the infinitesimal
align:start position:0%
integral over all the infinitesimal
volume and each infinitesimal volume
align:start position:0%
volume and each infinitesimal volume
align:start position:0%
volume and each infinitesimal volume
will have a certain density and will
align:start position:0%
will have a certain density and will
align:start position:0%
will have a certain density and will
contribute with you know with its own
align:start position:0%
contribute with you know with its own
align:start position:0%
contribute with you know with its own
density if the density is going to be
align:start position:0%
density if the density is going to be
align:start position:0%
density if the density is going to be
equal to here this will be the value of
align:start position:0%
equal to here this will be the value of
align:start position:0%
equal to here this will be the value of
the contribution of that infinitesimal
align:start position:0%
the contribution of that infinitesimal
align:start position:0%
the contribution of that infinitesimal
volume if the density somewhere else
align:start position:0%
volume if the density somewhere else
align:start position:0%
volume if the density somewhere else
corresponds to this this will be the
align:start position:0%
corresponds to this this will be the
align:start position:0%
corresponds to this this will be the
correspondent so we really patch up this
align:start position:0%
correspondent so we really patch up this
align:start position:0%
correspondent so we really patch up this
overall
align:start position:0%
overall
align:start position:0%
overall
exchange correlation term from all the
align:start position:0%
exchange correlation term from all the
align:start position:0%
exchange correlation term from all the
little infinitesimal volume exactly as
align:start position:0%
little infinitesimal volume exactly as
align:start position:0%
little infinitesimal volume exactly as
Thomas Fermi had done but now we do it
align:start position:0%
Thomas Fermi had done but now we do it
align:start position:0%
Thomas Fermi had done but now we do it
for a
align:start position:0%
for a
align:start position:0%
for a
atoma that is a much smaller term in our
align:start position:0%
atoma that is a much smaller term in our
align:start position:0%
atoma that is a much smaller term in our
problem Thomas and Fermi at Donita for
align:start position:0%
problem Thomas and Fermi at Donita for
align:start position:0%
problem Thomas and Fermi at Donita for
the quantum kinetic energy instead what
align:start position:0%
the quantum kinetic energy instead what
align:start position:0%
the quantum kinetic energy instead what
connection do it they do it for what is
align:start position:0%
connection do it they do it for what is
align:start position:0%
connection do it they do it for what is
left from their Universal functional
align:start position:0%
left from their Universal functional
align:start position:0%
left from their Universal functional
once you have taken out of the
align:start position:0%
once you have taken out of the
align:start position:0%
once you have taken out of the
electrostatic and once you have taken
align:start position:0%
electrostatic and once you have taken
align:start position:0%
electrostatic and once you have taken
out the quantum kinetic energy of the
align:start position:0%
out the quantum kinetic energy of the
align:start position:0%
out the quantum kinetic energy of the
non-interacting electrons at this point
align:start position:0%
non-interacting electrons at this point
align:start position:0%
non-interacting electrons at this point
in time
align:start position:0%
in time
align:start position:0%
in time
if you want 1980 and even before without
align:start position:0%
if you want 1980 and even before without
align:start position:0%
if you want 1980 and even before without
the computation with some sort of
align:start position:0%
the computation with some sort of
align:start position:0%
the computation with some sort of
analytical approximations to this curve
align:start position:0%
analytical approximations to this curve
align:start position:0%
analytical approximations to this curve
the inste functional theory becomes not
align:start position:0%
the inste functional theory becomes not
align:start position:0%
the inste functional theory becomes not
only a theory but also a practical
align:start position:0%
only a theory but also a practical
align:start position:0%
only a theory but also a practical
algorithm we have a sort of expression
align:start position:0%
algorithm we have a sort of expression
align:start position:0%
algorithm we have a sort of expression
for the exchange correlation term and so
align:start position:0%
for the exchange correlation term and so
align:start position:0%
for the exchange correlation term and so
now it's just a matter of trying to find
align:start position:0%
now it's just a matter of trying to find
align:start position:0%
now it's just a matter of trying to find
out what the solution to these problems
align:start position:0%
out what the solution to these problems
align:start position:0%
out what the solution to these problems
are and because somehow conceptually we
align:start position:0%
are and because somehow conceptually we
align:start position:0%
are and because somehow conceptually we
start from the homogeneous electron gasa
align:start position:0%
start from the homogeneous electron gasa
align:start position:0%
start from the homogeneous electron gasa
it turns out that you know this approach
align:start position:0%
it turns out that you know this approach
align:start position:0%
it turns out that you know this approach
worked especially well for solids I mean
align:start position:0%
worked especially well for solids I mean
align:start position:0%
worked especially well for solids I mean
the valence electrons in a solid
align:start position:0%
the valence electrons in a solid
align:start position:0%
the valence electrons in a solid
are a much less structured than the
align:start position:0%
are a much less structured than the
align:start position:0%
are a much less structured than the
electrons in a molecule that you know
align:start position:0%
electrons in a molecule that you know
align:start position:0%
electrons in a molecule that you know
they need to drop to zero so the charge
align:start position:0%
they need to drop to zero so the charge
align:start position:0%
they need to drop to zero so the charge
dance in a solid overall varies less
align:start position:0%
dance in a solid overall varies less
align:start position:0%
dance in a solid overall varies less
dramatically as a function of space than
align:start position:0%
dramatically as a function of space than
align:start position:0%
dramatically as a function of space than
the electron density in atoms and
align:start position:0%
the electron density in atoms and
align:start position:0%
the electron density in atoms and
molecules and these are actually sort of
align:start position:0%
molecules and these are actually sort of
align:start position:0%
molecules and these are actually sort of
you know what were summarized that the
align:start position:0%
you know what were summarized that the
align:start position:0%
you know what were summarized that the
numerical result of separately and Dalda
align:start position:0%
numerical result of separately and Dalda
align:start position:0%
numerical result of separately and Dalda
so they had calculated this exchange
align:start position:0%
so they had calculated this exchange
align:start position:0%
so they had calculated this exchange
correlation energy as a function of the
align:start position:0%
correlation energy as a function of the
align:start position:0%
correlation energy as a function of the
density and that was actually a
align:start position:0%
density and that was actually a
align:start position:0%
density and that was actually a
computational curve a set of dots and
align:start position:0%
computational curve a set of dots and
align:start position:0%
computational curve a set of dots and
this is often cited again Purdue and
align:start position:0%
this is often cited again Purdue and
align:start position:0%
this is often cited again Purdue and
zoomer in a sort of paper of death among
align:start position:0%
zoomer in a sort of paper of death among
align:start position:0%
zoomer in a sort of paper of death among
other things a sort of you know
align:start position:0%
other things a sort of you know
align:start position:0%
other things a sort of you know
suggested
align:start position:0%
suggested
align:start position:0%
suggested
analytical interpolation of all the
align:start position:0%
analytical interpolation of all the
align:start position:0%
analytical interpolation of all the
numerical data and so you see it
align:start position:0%
numerical data and so you see it
align:start position:0%
numerical data and so you see it
something somehow exotic but once it's
align:start position:0%
something somehow exotic but once it's
align:start position:0%
something somehow exotic but once it's
defined this is just not even a
align:start position:0%
defined this is just not even a
align:start position:0%
defined this is just not even a
functional is just a function of the
align:start position:0%
functional is just a function of the
align:start position:0%
functional is just a function of the
charge density so it's something that is
align:start position:0%
charge density so it's something that is
align:start position:0%
charge density so it's something that is
very simple to calculate
align:start position:0%
very simple to calculate
align:start position:0%
very simple to calculate
in practice and so at this point density
align:start position:0%
in practice and so at this point density
align:start position:0%
in practice and so at this point density
functional theory is a well-defined
align:start position:0%
functional theory is a well-defined
align:start position:0%
functional theory is a well-defined
theory so you see 1980 Satterlee and
align:start position:0%
theory so you see 1980 Satterlee and
align:start position:0%
theory so you see 1980 Satterlee and
alder do this quantum Monte Carlo
align:start position:0%
alder do this quantum Monte Carlo
align:start position:0%
alder do this quantum Monte Carlo
calculation find out sort of what is
align:start position:0%
calculation find out sort of what is
align:start position:0%
calculation find out sort of what is
this exchange correlation energy per
align:start position:0%
this exchange correlation energy per
align:start position:0%
this exchange correlation energy per
doing zoom can write out a simple
align:start position:0%
doing zoom can write out a simple
align:start position:0%
doing zoom can write out a simple
interpolation 1982 sort of the first
align:start position:0%
interpolation 1982 sort of the first
align:start position:0%
interpolation 1982 sort of the first
time that I think we see sort of where
align:start position:0%
time that I think we see sort of where
align:start position:0%
time that I think we see sort of where
all of this is going Marvin Cohen in
align:start position:0%
all of this is going Marvin Cohen in
align:start position:0%
all of this is going Marvin Cohen in
Berkeley sort of you know has been
align:start position:0%
Berkeley sort of you know has been
align:start position:0%
Berkeley sort of you know has been
working for two or three years
align:start position:0%
working for two or three years
align:start position:0%
working for two or three years
aleksander was that reason him number of
align:start position:0%
aleksander was that reason him number of
align:start position:0%
aleksander was that reason him number of
his students they have been able to
align:start position:0%
his students they have been able to
align:start position:0%
his students they have been able to
actually write out all the electronic
align:start position:0%
actually write out all the electronic
align:start position:0%
actually write out all the electronic
structure codes that are able to solve
align:start position:0%
structure codes that are able to solve
align:start position:0%
structure codes that are able to solve
the density functional equation for the
align:start position:0%
the density functional equation for the
align:start position:0%
the density functional equation for the
case of a periodic solid and so they
align:start position:0%
case of a periodic solid and so they
align:start position:0%
case of a periodic solid and so they
address the case of silicon sort of the
align:start position:0%
address the case of silicon sort of the
align:start position:0%
address the case of silicon sort of the
most important material in electronics
align:start position:0%
most important material in electronics
align:start position:0%
most important material in electronics
and so what they do is they're able now
align:start position:0%
and so what they do is they're able now
align:start position:0%
and so what they do is they're able now
to calculate you know the energy of that
align:start position:0%
to calculate you know the energy of that
align:start position:0%
to calculate you know the energy of that
system as a function of the atomic
align:start position:0%
system as a function of the atomic
align:start position:0%
system as a function of the atomic
position and in particular as a function
align:start position:0%
position and in particular as a function
align:start position:0%
position and in particular as a function
of the lattice parameter so you know
align:start position:0%
of the lattice parameter so you know
align:start position:0%
of the lattice parameter so you know
first thing that they do is they take
align:start position:0%
first thing that they do is they take
align:start position:0%
first thing that they do is they take
silicon in it die among the structure so
align:start position:0%
silicon in it die among the structure so
align:start position:0%
silicon in it die among the structure so
you know the FCC lattice with two atoms
align:start position:0%
you know the FCC lattice with two atoms
align:start position:0%
you know the FCC lattice with two atoms
as a basis and they calculate that
align:start position:0%
as a basis and they calculate that
align:start position:0%
as a basis and they calculate that
energy as a function of the lattice
align:start position:0%
energy as a function of the lattice
align:start position:0%
energy as a function of the lattice
parameter and it looks something like
align:start position:0%
parameter and it looks something like
align:start position:0%
parameter and it looks something like
this and then obviously you know as you
align:start position:0%
this and then obviously you know as you
align:start position:0%
this and then obviously you know as you
have learned by now you look at what is
align:start position:0%
have learned by now you look at what is
align:start position:0%
have learned by now you look at what is
the minimum of that energy and it is the
align:start position:0%
the minimum of that energy and it is the
align:start position:0%
the minimum of that energy and it is the
theoretical prediction of the lattice
align:start position:0%
theoretical prediction of the lattice
align:start position:0%
theoretical prediction of the lattice
parameter and this Mac on you know one
align:start position:0%
parameter and this Mac on you know one
align:start position:0%
parameter and this Mac on you know one
percent error they look at the second
align:start position:0%
percent error they look at the second
align:start position:0%
percent error they look at the second
derivative this curvature here is really
align:start position:0%
derivative this curvature here is really
align:start position:0%
derivative this curvature here is really
the bulk models of your problem again
align:start position:0%
the bulk models of your problem again
align:start position:0%
the bulk models of your problem again
you know five ten percent error and then
align:start position:0%
you know five ten percent error and then
align:start position:0%
you know five ten percent error and then
they say well let's suppose that we have
align:start position:0%
they say well let's suppose that we have
align:start position:0%
they say well let's suppose that we have
silicon not in the diamond phase but
align:start position:0%
silicon not in the diamond phase but
align:start position:0%
silicon not in the diamond phase but
let's suppose that we have silicon in
align:start position:0%
let's suppose that we have silicon in
align:start position:0%
let's suppose that we have silicon in
the beta T in phase and so you know this
align:start position:0%
the beta T in phase and so you know this
align:start position:0%
the beta T in phase and so you know this
is also experimentally known and we know
align:start position:0%
is also experimentally known and we know
align:start position:0%
is also experimentally known and we know
in the better teen what is the lattice
align:start position:0%
in the better teen what is the lattice
align:start position:0%
in the better teen what is the lattice
parameter of silicon and we know from
align:start position:0%
parameter of silicon and we know from
align:start position:0%
parameter of silicon and we know from
the Maxwell construction what is the
align:start position:0%
the Maxwell construction what is the
align:start position:0%
the Maxwell construction what is the
pressure
align:start position:0%
pressure
align:start position:0%
pressure
at which we would have a transition from
align:start position:0%
at which we would have a transition from
align:start position:0%
at which we would have a transition from
say diamanda to beta Tina and again you
align:start position:0%
say diamanda to beta Tina and again you
align:start position:0%
say diamanda to beta Tina and again you
know I can't remember what was the error
align:start position:0%
know I can't remember what was the error
align:start position:0%
know I can't remember what was the error
but is substantially correct and you
align:start position:0%
but is substantially correct and you
align:start position:0%
but is substantially correct and you
know they were able to actually sort of
align:start position:0%
know they were able to actually sort of
align:start position:0%
know they were able to actually sort of
calculate the sort of complex zoology of
align:start position:0%
calculate the sort of complex zoology of
align:start position:0%
calculate the sort of complex zoology of
all the high pressure phases of silicon
align:start position:0%
all the high pressure phases of silicon
align:start position:0%
all the high pressure phases of silicon
and it was in remarkable agreement with
align:start position:0%
and it was in remarkable agreement with
align:start position:0%
and it was in remarkable agreement with
experiment so 1982 this is the in
align:start position:0%
experiment so 1982 this is the in
align:start position:0%
experiment so 1982 this is the in
enjoyment in particular Marvin Cohen in
align:start position:0%
enjoyment in particular Marvin Cohen in
align:start position:0%
enjoyment in particular Marvin Cohen in
Berkeley shows that you know for a--
align:start position:0%
align:start position:0%
Marvin
align:start position:0%
align:start position:0%
Cohen for a realistic case' density
align:start position:0%
Cohen for a realistic case' density
align:start position:0%
Cohen for a realistic case' density
functional theory is able really to give
align:start position:0%
functional theory is able really to give
align:start position:0%
functional theory is able really to give
us quantitative prediction Marvin Cohen
align:start position:0%
us quantitative prediction Marvin Cohen
align:start position:0%
us quantitative prediction Marvin Cohen
has actually become this year the
align:start position:0%
has actually become this year the
align:start position:0%
has actually become this year the
president of the American Physical
align:start position:0%
president of the American Physical
align:start position:0%
president of the American Physical
Society okay so this is really the
align:start position:0%
Society okay so this is really the
align:start position:0%
Society okay so this is really the
beginning of density functional theory
align:start position:0%
beginning of density functional theory
align:start position:0%
beginning of density functional theory
as a practical approach and in many ways
align:start position:0%
as a practical approach and in many ways
align:start position:0%
as a practical approach and in many ways
what has happened between
align:start position:0%
what has happened between
align:start position:0%
what has happened between
1982 and today is that we have become
align:start position:0%
1982 and today is that we have become
align:start position:0%
1982 and today is that we have become
better and better at solving the
align:start position:0%
better and better at solving the
align:start position:0%
better and better at solving the
algorithm for this overall still complex
align:start position:0%
algorithm for this overall still complex
align:start position:0%
algorithm for this overall still complex
computational problem and you see a lot
align:start position:0%
computational problem and you see a lot
align:start position:0%
computational problem and you see a lot
of this in the next two lectures that
align:start position:0%
of this in the next two lectures that
align:start position:0%
of this in the next two lectures that
follows and we have become
align:start position:0%
follows and we have become
align:start position:0%
follows and we have become
somewhat better not really dramatically
align:start position:0%
somewhat better not really dramatically
align:start position:0%
somewhat better not really dramatically
better in calculating that exchange
align:start position:0%
better in calculating that exchange
align:start position:0%
better in calculating that exchange
correlation energy in a way sort of you
align:start position:0%
correlation energy in a way sort of you
align:start position:0%
correlation energy in a way sort of you
know the ideas of
align:start position:0%
know the ideas of
align:start position:0%
know the ideas of
Coney Shama from 1965 of having a local
align:start position:0%
Coney Shama from 1965 of having a local
align:start position:0%
Coney Shama from 1965 of having a local
density approximation is still very good
align:start position:0%
density approximation is still very good
align:start position:0%
density approximation is still very good
I mean it's not used nowadays anymore
align:start position:0%
I mean it's not used nowadays anymore
align:start position:0%
I mean it's not used nowadays anymore
that much but you know it's as close as
align:start position:0%
that much but you know it's as close as
align:start position:0%
that much but you know it's as close as
you know what we can do now is not
align:start position:0%
you know what we can do now is not
align:start position:0%
you know what we can do now is not
really that much better and you know as
align:start position:0%
really that much better and you know as
align:start position:0%
really that much better and you know as
you can imagine sort of you know what
align:start position:0%
you can imagine sort of you know what
align:start position:0%
you can imagine sort of you know what
people have done that was a bit better
align:start position:0%
people have done that was a bit better
align:start position:0%
people have done that was a bit better
was introducing gradients in your
align:start position:0%
was introducing gradients in your
align:start position:0%
was introducing gradients in your
problem so you have you're trying to
align:start position:0%
problem so you have you're trying to
align:start position:0%
problem so you have you're trying to
guess what the energy of an
align:start position:0%
guess what the energy of an
align:start position:0%
guess what the energy of an
inhomogeneous system comes
align:start position:0%
inhomogeneous system comes
align:start position:0%
inhomogeneous system comes
starting from what you know about the
align:start position:0%
starting from what you know about the
align:start position:0%
starting from what you know about the
homogeneous electron Gaza well maybe you
align:start position:0%
homogeneous electron Gaza well maybe you
align:start position:0%
homogeneous electron Gaza well maybe you
should somehow throw in into your
align:start position:0%
should somehow throw in into your
align:start position:0%
should somehow throw in into your
problem also the first derivative the
align:start position:0%
problem also the first derivative the
align:start position:0%
problem also the first derivative the
gradient of the density and so people
align:start position:0%
gradient of the density and so people
align:start position:0%
gradient of the density and so people
did that fairly sooner in the early 80s
align:start position:0%
did that fairly sooner in the early 80s
align:start position:0%
did that fairly sooner in the early 80s
and sort of you using the gradients was
align:start position:0%
and sort of you using the gradients was
align:start position:0%
and sort of you using the gradients was
actually much worse there is there was
align:start position:0%
actually much worse there is there was
align:start position:0%
actually much worse there is there was
you know a miracle in the local density
align:start position:0%
you know a miracle in the local density
align:start position:0%
you know a miracle in the local density
approximation in which the actual
align:start position:0%
approximation in which the actual
align:start position:0%
approximation in which the actual
expression of the local density
align:start position:0%
expression of the local density
align:start position:0%
expression of the local density
approximation satisfy satisfies a lot of
align:start position:0%
approximation satisfy satisfies a lot of
align:start position:0%
approximation satisfy satisfies a lot of
symmetry properties and scaling
align:start position:0%
symmetry properties and scaling
align:start position:0%
symmetry properties and scaling
properties of what would be the exact
align:start position:0%
properties of what would be the exact
align:start position:0%
properties of what would be the exact
exchange correlation functional the time
align:start position:0%
exchange correlation functional the time
align:start position:0%
exchange correlation functional the time
people patina gradients all these sort
align:start position:0%
people patina gradients all these sort
align:start position:0%
people patina gradients all these sort
of you know symmetries and scaling
align:start position:0%
of you know symmetries and scaling
align:start position:0%
of you know symmetries and scaling
properties were sort of thrown to the
align:start position:0%
properties were sort of thrown to the
align:start position:0%
properties were sort of thrown to the
dogs and actually the GGAs sorry them
align:start position:0%
dogs and actually the GGAs sorry them
align:start position:0%
dogs and actually the GGAs sorry them
the gradient approximation were working
align:start position:0%
the gradient approximation were working
align:start position:0%
the gradient approximation were working
much much worse and so people needed to
align:start position:0%
much much worse and so people needed to
align:start position:0%
much much worse and so people needed to
realize a sort of in the late
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realize a sort of in the late
align:start position:0%
realize a sort of in the late
80s at the work of axle-back a of John
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80s at the work of axle-back a of John
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80s at the work of axle-back a of John
Purdue especially a lotta that you sort
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Purdue especially a lotta that you sort
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Purdue especially a lotta that you sort
of need to introduce gradients in ways
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of need to introduce gradients in ways
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of need to introduce gradients in ways
that still satisfy a lot of the these
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that still satisfy a lot of the these
align:start position:0%
that still satisfy a lot of the these
analytical forms and in many ways by now
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analytical forms and in many ways by now
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analytical forms and in many ways by now
there is a sort of generalized
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there is a sort of generalized
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there is a sort of generalized
exchange correlation functional that
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exchange correlation functional that
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exchange correlation functional that
being set of developed in the mid 90s by
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being set of developed in the mid 90s by
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being set of developed in the mid 90s by
/ - Kieran Burke now at Rutgers and
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/ - Kieran Burke now at Rutgers and
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/ - Kieran Burke now at Rutgers and
Matthew but yes elder horf that is
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Matthew but yes elder horf that is
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Matthew but yes elder horf that is
called the PBE functional that is
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called the PBE functional that is
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called the PBE functional that is
becoming a sort of the workhorse so a
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becoming a sort of the workhorse so a
align:start position:0%
becoming a sort of the workhorse so a
lot of the time you see sort of density
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lot of the time you see sort of density
align:start position:0%
lot of the time you see sort of density
functional calculation than in the PBE
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functional calculation than in the PBE
align:start position:0%
functional calculation than in the PBE
GGA approximation but again you know
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GGA approximation but again you know
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GGA approximation but again you know
these are important improvements but if
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these are important improvements but if
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these are important improvements but if
you want just you know sort of very
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you want just you know sort of very
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you want just you know sort of very
little on top of the local density
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little on top of the local density
align:start position:0%
little on top of the local density
approximation of the sixties
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approximation of the sixties
align:start position:0%
approximation of the sixties
the chemistry community is also sort of
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the chemistry community is also sort of
align:start position:0%
the chemistry community is also sort of
you know than a number of very
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you know than a number of very
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you know than a number of very
intriguing
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intriguing
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intriguing
developments in particular there are
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developments in particular there are
align:start position:0%
developments in particular there are
things that are Treefolk does very well
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things that are Treefolk does very well
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things that are Treefolk does very well
in particular because you have the sort
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in particular because you have the sort
align:start position:0%
in particular because you have the sort
of exchange term in hartree-fock you
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of exchange term in hartree-fock you
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of exchange term in hartree-fock you
cancel remember the self interaction say
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cancel remember the self interaction say
align:start position:0%
cancel remember the self interaction say
in the single electron problem coming
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in the single electron problem coming
align:start position:0%
in the single electron problem coming
from the heart rate electrostatic
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from the heart rate electrostatic
align:start position:0%
from the heart rate electrostatic
problem the instant functional theory in
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problem the instant functional theory in
align:start position:0%
problem the instant functional theory in
theory in its exact formulation would be
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theory in its exact formulation would be
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theory in its exact formulation would be
self interaction corrected but in
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self interaction corrected but in
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self interaction corrected but in
practice it is not if you solve the
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practice it is not if you solve the
align:start position:0%
practice it is not if you solve the
hydrogen atom with density functional
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hydrogen atom with density functional
align:start position:0%
hydrogen atom with density functional
theory you have that the electron
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theory you have that the electron
align:start position:0%
theory you have that the electron
interacts with the charge density
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interacts with the charge density
align:start position:0%
interacts with the charge density
created by this thing by the electron
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created by this thing by the electron
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created by this thing by the electron
itself and so what sort of the quantum
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itself and so what sort of the quantum
align:start position:0%
itself and so what sort of the quantum
chemistry community is Danna is well
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chemistry community is Danna is well
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chemistry community is Danna is well
they said let's take you know Lda is
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they said let's take you know Lda is
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they said let's take you know Lda is
like that only take ggas that seemed to
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like that only take ggas that seemed to
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like that only take ggas that seemed to
work very well but let's actually
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work very well but let's actually
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work very well but let's actually
construct an exchange correlation
align:start position:0%
construct an exchange correlation
align:start position:0%
construct an exchange correlation
functional that has a little bit of disa
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functional that has a little bit of disa
align:start position:0%
functional that has a little bit of disa
but got also a little bit of what we
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but got also a little bit of what we
align:start position:0%
but got also a little bit of what we
know worked well in the hartree-fock
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know worked well in the hartree-fock
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know worked well in the hartree-fock
equation so they construct hybrid
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equation so they construct hybrid
align:start position:0%
equation so they construct hybrid
functional in which there are sort of
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functional in which there are sort of
align:start position:0%
functional in which there are sort of
pure density functional terms and sort
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pure density functional terms and sort
align:start position:0%
pure density functional terms and sort
of our three fork exchange term mixed in
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of our three fork exchange term mixed in
align:start position:0%
of our three fork exchange term mixed in
it makes the equation much more complex
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it makes the equation much more complex
align:start position:0%
it makes the equation much more complex
and if you want a is a set of less pure
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and if you want a is a set of less pure
align:start position:0%
and if you want a is a set of less pure
formulation of density functional theory
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formulation of density functional theory
align:start position:0%
formulation of density functional theory
but it can work reasonably well or very
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but it can work reasonably well or very
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but it can work reasonably well or very
well especially again for atoms and
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well especially again for atoms and
align:start position:0%
well especially again for atoms and
molecules and this is a this is where we
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molecules and this is a this is where we
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molecules and this is a this is where we
are basically with exchange correlation
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are basically with exchange correlation
align:start position:0%
are basically with exchange correlation
functional I think I'll stop here for
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functional I think I'll stop here for
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functional I think I'll stop here for
today because it's a - a lot of work
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today because it's a - a lot of work
align:start position:0%
today because it's a - a lot of work
what we'll start seeing in the next
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what we'll start seeing in the next
align:start position:0%
what we'll start seeing in the next
class is a sort of you know how we
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class is a sort of you know how we
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class is a sort of you know how we
actually solve this equation in practice
align:start position:0%
actually solve this equation in practice
align:start position:0%
actually solve this equation in practice
on march 8th you will go into your
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on march 8th you will go into your
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on march 8th you will go into your
second lab in which you'll actually
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second lab in which you'll actually
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second lab in which you'll actually
study the energy of a solid using
align:start position:0%
study the energy of a solid using
align:start position:0%
study the energy of a solid using
density functional theory what I said
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density functional theory what I said
align:start position:0%
density functional theory what I said
today is probably the last of the
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today is probably the last of the
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today is probably the last of the
conceptual lectures and I understand
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conceptual lectures and I understand
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conceptual lectures and I understand
that some of it is very complex there
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that some of it is very complex there
align:start position:0%
that some of it is very complex there
are a-- there is reading material posted
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are a-- there is reading material posted
align:start position:0%
are a-- there is reading material posted
on the stellar website there is the
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on the stellar website there is the
align:start position:0%
on the stellar website there is the
corner of get opals paper on the insta
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corner of get opals paper on the insta
align:start position:0%
corner of get opals paper on the insta
functional theory and some of the
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functional theory and some of the
align:start position:0%
functional theory and some of the
readings that I've given are very useful
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readings that I've given are very useful
align:start position:0%
readings that I've given are very useful
that the two best books that are also
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that the two best books that are also
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that the two best books that are also
cited at the end of this lecture are
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cited at the end of this lecture are
align:start position:0%
cited at the end of this lecture are
probably the one by hawker or the one by
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probably the one by hawker or the one by
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probably the one by hawker or the one by
power and young both called the density
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power and young both called the density
align:start position:0%
power and young both called the density
functional Theory or density functional
align:start position:0%
functional Theory or density functional
align:start position:0%
functional Theory or density functional
theory in practice and they are cited on
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theory in practice and they are cited on
align:start position:0%
theory in practice and they are cited on
the last page otherwise er this is it
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the last page otherwise er this is it
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the last page otherwise er this is it
for today and see you next week