| """ |
| Naturalunit system. |
| |
| The natural system comes from "setting c = 1, hbar = 1". From the computer |
| point of view it means that we use velocity and action instead of length and |
| time. Moreover instead of mass we use energy. |
| """ |
|
|
| from sympy.physics.units import DimensionSystem |
| from sympy.physics.units.definitions import c, eV, hbar |
| from sympy.physics.units.definitions.dimension_definitions import ( |
| action, energy, force, frequency, length, mass, momentum, |
| power, time, velocity) |
| from sympy.physics.units.prefixes import PREFIXES, prefix_unit |
| from sympy.physics.units.unitsystem import UnitSystem |
|
|
|
|
| |
| _natural_dim = DimensionSystem( |
| base_dims=(action, energy, velocity), |
| derived_dims=(length, mass, time, momentum, force, power, frequency) |
| ) |
|
|
| units = prefix_unit(eV, PREFIXES) |
|
|
| |
| natural = UnitSystem(base_units=(hbar, eV, c), units=units, name="Natural system") |
|
|
