File size: 3,780 Bytes
afe68b4
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
import itertools
from pathlib import Path

import numpy as np
from ase import Atom, Atoms
from ase.calculators.calculator import BaseCalculator
from ase.data import chemical_symbols, covalent_radii, vdw_alvarez
from ase.io import read, write
from prefect import flow, task
from tqdm.auto import tqdm

from mlip_arena.models import REGISTRY, MLIPEnum
from mlip_arena.tasks.utils import get_calculator


@task
def homonuclear_diatomic(symbol: str, calculator: BaseCalculator, out_dir: Path):
    """
    Calculate the potential energy curve for single homonuclear diatomic molecule.

    This function computes the potential energy of a diatomic molecule (two atoms of
    the same element) across a range of interatomic distances. The distance range is
    automatically determined from the covalent and van der Waals radii of the element.

    Args:
        symbol: Chemical symbol of the atom (e.g., 'H', 'O', 'Fe')
        calculator: ASE calculator object used to compute the potential energies. Could be VASP, MLIP, etc.

    Returns:
        None: Results are saved as trajectory files in a directory structure:
              /{model_family}/{element_pair}/{model_name}.extxyz

    Note:
        - Minimum distance is set to 0.9× the covalent radius
        - Maximum distance is set to 3.1× the van der Waals radius (or 6 Å if unknown)
        - Distance step size is fixed at 0.01 Å
        - If an existing trajectory file is found, the calculation will resume from where it left off
        - The atoms are placed in a periodic box large enough to avoid self-interaction
    """

    atom = Atom(symbol)
    rmin = 0.9 * covalent_radii[atom.number]
    rvdw = (
        vdw_alvarez.vdw_radii[atom.number]
        if atom.number < len(vdw_alvarez.vdw_radii)
        else np.nan
    )
    rmax = 3.1 * rvdw if not np.isnan(rvdw) else 6
    rstep = 0.01
    npts = int((rmax - rmin) / rstep)

    rs = np.linspace(rmin, rmax, npts)
    es = np.zeros_like(rs)

    da = symbol + symbol

    out_dir.mkdir(parents=True, exist_ok=True)

    skip = 0

    a = 5 * rmax
    r = rs[0]

    positions = [
        [a / 2 - r / 2, a / 2, a / 2],
        [a / 2 + r / 2, a / 2, a / 2],
    ]

    traj_fpath = out_dir / f"{da!s}.extxyz"

    if traj_fpath.exists():
        traj = read(traj_fpath, index=":")
        skip = len(traj)
        atoms = traj[-1]
    else:
        # Create the unit cell with two atoms
        atoms = Atoms(
            da,
            positions=positions,
            # magmoms=magmoms,
            cell=[a, a + 0.001, a + 0.002],
            pbc=False,
        )

    atoms.calc = calculator

    for i, r in enumerate(tqdm(rs)):
        if i < skip:
            continue

        positions = [
            [a / 2 - r / 2, a / 2, a / 2],
            [a / 2 + r / 2, a / 2, a / 2],
        ]

        # atoms.set_initial_magnetic_moments(magmoms)
        atoms.set_positions(positions)
        es[i] = atoms.get_potential_energy()
        write(traj_fpath, atoms, append="a")


@flow
def homonuclear_diatomics(model: str | BaseCalculator, run_dir: Path):

    model = MLIPEnum[model] if isinstance(model, str) else model
    model_name = model.name if isinstance(model, MLIPEnum) else model.__class__.__name__

    futures = []

    for symbol in chemical_symbols[1:]:
        out_dir = run_dir / model_name
        calculator = get_calculator(model)
        future = homonuclear_diatomic.submit(
            symbol,
            calculator,
            out_dir=out_dir,
        )
        futures.append(future)

    return [f.result(raise_on_failure=False) for f in futures]


if __name__ == "__main__":
    homonuclear_diatomics.with_options(
        # task_runner=DaskTaskRunner(address=client.scheduler.address),
        log_prints=True,
    )()