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Implement lattice transform to upper-triangular matrix for ASE Nose-Hoover thermostat #68

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merged 9 commits into from
Sep 12, 2023
Merged

Implement lattice transform to upper-triangular matrix for ASE Nose-Hoover thermostat #68

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0db053c
Implemented transformation of lattice to upper-triangular matrix
Sep 11, 2023
dfd8bc4
Added verbose flag and explanation to upper_triangular_cell
Sep 11, 2023
1beaf1b
FIXED: ASE NPT does not accept externalstress=None
Sep 12, 2023
f22adc1
Added tests for Nose-Hoover NVT and NPT MD
Sep 12, 2023
a6480fd
Changed MD test numerical tolerance
Sep 12, 2023
a976874
use numpy.testing.assert_allclose over np.isclose().all() for better …
janosh Sep 12, 2023
cfba1c9
tweak upper_triangular_cell() doc str
janosh Sep 12, 2023
055b8ed
Merge branch 'main' into upper_triangular_cell
janosh Sep 12, 2023
948a8bd
fix black
janosh Sep 12, 2023
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34 changes: 33 additions & 1 deletion chgnet/model/dynamics.py
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Original file line number Diff line number Diff line change
Expand Up @@ -479,12 +479,14 @@ def __init__(
Nose-hoover (constant N, V, T) molecular dynamics.
ASE implementation currently only supports upper triangular lattice
"""
self.upper_triangular_cell(verbose=False)
self.dyn = NPT(
atoms=self.atoms,
timestep=timestep * units.fs,
temperature_K=temperature,
externalstress=pressure
* units.GPa, # ase NPT does not like externalstress=None
ttime=taut * units.fs,
externalstress=None,
pfactor=None,
trajectory=trajectory,
logfile=logfile,
Expand Down Expand Up @@ -551,6 +553,7 @@ def __init__(
see: https://gitlab.com/ase/ase/-/blob/master/ase/md/npt.py
ASE implementation currently only supports upper triangular lattice
"""
self.upper_triangular_cell(verbose=False)
ptime = taup * units.fs
self.dyn = NPT(
atoms=self.atoms,
Expand Down Expand Up @@ -651,6 +654,35 @@ def set_atoms(self, atoms: Atoms):
self.dyn.atoms = atoms
self.dyn.atoms.calc = calculator

def upper_triangular_cell(self, verbose: bool | None = False):
"""Transform to upper-triangular cell.
ASE Nose-Hoover implementation only supports upper-triangular cell
while ASE's canonical description is lower-triangular cell.

Args:
verbose (bool): Whether to print the status of cell transformation.
Default = False
Returns:
"""
if not NPT._isuppertriangular(self.atoms.get_cell()):
a, b, c, alpha, beta, gamma = self.atoms.cell.cellpar()
ang = np.radians((alpha, beta, gamma))
sina, sinb, sing = np.sin(ang)
cosa, cosb, cosg = np.cos(ang)
cosp = (cosg - cosa * cosb) / (sina * sinb)
cosp = np.clip(cosp, -1.0, 1.0)
sinp = np.sqrt(1.0 - cosp**2.0)

new_basis = [
(a * sinb * sinp, a * sinb * cosp, a * cosb),
(0.0, b * sina, b * cosa),
(0.0, 0.0, c),
]

self.atoms.set_cell(new_basis, scale_atoms=True)
if verbose:
print("Transformed to upper triangular unit cell.", flush=True)


class EquationOfState:
"""Class to calculate equation of state."""
Expand Down
65 changes: 65 additions & 0 deletions examples/mp-1175469-Li9Co7O16.cif
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Original file line number Diff line number Diff line change
@@ -0,0 +1,65 @@
# generated using pymatgen
data_Li9Co7O16
_symmetry_space_group_name_H-M 'P 1'
_cell_length_a 6.30240647
_cell_length_b 6.30741300
_cell_length_c 7.41583051
_cell_angle_alpha 75.47000443
_cell_angle_beta 65.23135009
_cell_angle_gamma 72.00717747
_symmetry_Int_Tables_number 1
_chemical_formula_structural Li9Co7O16
_chemical_formula_sum 'Li9 Co7 O16'
_cell_volume 252.05269201
_cell_formula_units_Z 1
loop_
_symmetry_equiv_pos_site_id
_symmetry_equiv_pos_as_xyz
1 'x, y, z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
Li+ 1.0
Co3+ 3.0
Co4+ 4.0
O2- -2.0
loop_
_atom_site_type_symbol
_atom_site_label
_atom_site_symmetry_multiplicity
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
Li+ Li0 1 0.31442518 0.68680206 0.56469026 1
Li+ Li1 1 0.80552981 0.18376271 0.06064773 1
Li+ Li2 1 0.43695568 0.57151353 0.18253456 1
Li+ Li3 1 0.92705143 0.06026526 0.69553727 1
Li+ Li4 1 0.56304432 0.42848647 0.81746544 1
Li+ Li5 1 0.07294857 0.93973474 0.30446273 1
Li+ Li6 1 0.68557482 0.31319794 0.43530974 1
Li+ Li7 1 0.19447019 0.81623729 0.93935227 1
Li+ Li8 1 0.50000000 0.00000000 0.00000000 1
Co3+ Co9 1 0.87189169 0.62805253 0.87615769 1
Co3+ Co10 1 0.12810831 0.37194747 0.12384231 1
Co3+ Co11 1 0.37568054 0.12368956 0.37222619 1
Co3+ Co12 1 0.00000000 0.50000000 0.50000000 1
Co3+ Co13 1 0.62431946 0.87631044 0.62777381 1
Co4+ Co14 1 0.25225503 0.24664332 0.75326548 1
Co4+ Co15 1 0.74774497 0.75335668 0.24673452 1
O2- O16 1 0.20298483 0.51557922 0.85294009 1
O2- O17 1 0.70174803 0.01784432 0.35191128 1
O2- O18 1 0.32496647 0.38970329 0.47992830 1
O2- O19 1 0.84540853 0.88153215 0.97729332 1
O2- O20 1 0.44478863 0.28084762 0.11226145 1
O2- O21 1 0.95254917 0.76784039 0.60312012 1
O2- O22 1 0.57889279 0.14834865 0.71233501 1
O2- O23 1 0.07585520 0.64172837 0.22862318 1
O2- O24 1 0.42110721 0.85165135 0.28766499 1
O2- O25 1 0.92414480 0.35827163 0.77137682 1
O2- O26 1 0.55521137 0.71915238 0.88773855 1
O2- O27 1 0.04745083 0.23215961 0.39687988 1
O2- O28 1 0.67503353 0.61029671 0.52007170 1
O2- O29 1 0.15459147 0.11846785 0.02270668 1
O2- O30 1 0.79701517 0.48442078 0.14705991 1
O2- O31 1 0.29825197 0.98215568 0.64808872 1
113 changes: 113 additions & 0 deletions tests/test_md.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,13 @@
import numpy as np
import pytest
from ase import Atoms
from ase.md.npt import NPT
from ase.md.nptberendsen import Inhomogeneous_NPTBerendsen
from ase.md.nvtberendsen import NVTBerendsen
from ase.md.verlet import VelocityVerlet
from pymatgen.analysis.structure_matcher import StructureMatcher
from pymatgen.core import Structure
from pymatgen.io.ase import AseAtomsAdaptor
from pytest import MonkeyPatch, approx

from chgnet import ROOT
Expand All @@ -24,6 +27,7 @@

relaxer = StructOptimizer()
structure = Structure.from_file(f"{ROOT}/examples/mp-18767-LiMnO2.cif")
structure_2 = Structure.from_file(f"{ROOT}/examples/mp-1175469-Li9Co7O16.cif")
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Why is there a need to include LCO for Nose-Hoover test?

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Why is there a need to include LCO for Nose-Hoover test?

Because the cell matrix of LiMnO2 is diagonal.

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@bowen-bd bowen-bd Sep 12, 2023 •
edited
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This makes sense. Another way is to use rotation and non-diagonal supercell expansion to create a non-diagonal LiMnO2 cell

chgnet = CHGNet.load()


Expand Down Expand Up @@ -163,6 +167,115 @@ def test_md_npt_inhomogeneous_berendsen(tmp_path: Path, monkeypatch: MonkeyPatch
assert np.isclose(logs, ref, rtol=2.1e-3, atol=1e-8).all()


def test_md_nvt_nose_hoover(tmp_path: Path, monkeypatch: MonkeyPatch):
monkeypatch.chdir(tmp_path) # run MD in temporary directory

md = MolecularDynamics(
atoms=structure_2,
model=chgnet,
ensemble="nvt",
thermostat="nose-hoover",
temperature=1000, # in k
timestep=2, # in fs
trajectory="md_out.traj",
logfile="md_out.log",
loginterval=10,
)

new_atoms = AseAtomsAdaptor.get_structure(md.atoms)
assert StructureMatcher(
primitive_cell=False, scale=False, attempt_supercell=False, allow_subset=False
).fit(structure_2, new_atoms)

md.run(100)

assert isinstance(md.atoms, Atoms)
assert isinstance(md.atoms.calc, CHGNetCalculator)
assert isinstance(md.dyn, NPT)
assert np.isclose(
md.dyn.externalstress,
[-6.324e-07, -6.324e-07, -6.324e-07, 0.0, 0.0, 0.0],
rtol=1e-4,
atol=1e-8,
).all()
assert os.path.isfile("md_out.traj")
assert os.path.isfile("md_out.log")
with open("md_out.log") as log_file:
next(log_file)
logs = log_file.read()
logs = np.fromstring(logs, dtype=float, sep=" ")
ref = np.fromstring(
"0.0200 -199.2479 -199.3994 0.1515 36.6\n"
"0.0400 -199.2459 -199.3440 0.0981 23.7\n"
"0.0600 -199.2394 -199.2669 0.0275 6.6\n"
"0.0800 -199.2348 -199.4143 0.1795 43.4\n"
"0.1000 -199.2274 -199.2774 0.0500 12.1\n"
"0.1200 -199.2123 -199.3001 0.0878 21.2\n"
"0.1400 -199.2040 -199.4000 0.1961 47.4\n"
"0.1600 -199.1856 -199.2181 0.0325 7.9\n"
"0.1800 -199.1603 -199.3266 0.1662 40.2\n"
"0.2000 -199.1455 -199.3490 0.2035 49.2\n",
dtype=float,
sep=" ",
)
assert np.isclose(logs, ref, rtol=1e-2, atol=1e-7).all()


def test_md_npt_nose_hoover(tmp_path: Path, monkeypatch: MonkeyPatch):
monkeypatch.chdir(tmp_path) # run MD in temporary directory

md = MolecularDynamics(
atoms=structure_2,
model=chgnet,
ensemble="npt",
thermostat="nose-hoover",
temperature=1000, # in k
timestep=2, # in fs
trajectory="md_out.traj",
logfile="md_out.log",
loginterval=10,
)

new_atoms = AseAtomsAdaptor.get_structure(md.atoms)
assert StructureMatcher(
primitive_cell=False, scale=False, attempt_supercell=False, allow_subset=False
).fit(structure_2, new_atoms)

md.run(100)

assert isinstance(md.atoms, Atoms)
assert isinstance(md.atoms.calc, CHGNetCalculator)
assert isinstance(md.dyn, NPT)
assert md.bulk_modulus == approx(102.977, rel=1e-2)
assert np.isclose(
md.dyn.externalstress,
[-6.324e-07, -6.324e-07, -6.324e-07, 0.0, 0.0, 0.0],
rtol=1e-4,
atol=1e-8,
).all()
assert os.path.isfile("md_out.traj")
assert os.path.isfile("md_out.log")
with open("md_out.log") as log_file:
next(log_file)
logs = log_file.read()
logs = np.fromstring(logs, dtype=float, sep=" ")
ref = np.fromstring(
"0.0200 -199.2480 -199.3994 0.1514 36.6\n"
"0.0400 -199.2460 -199.3442 0.0982 23.7\n"
"0.0600 -199.2397 -199.2672 0.0275 6.7\n"
"0.0800 -199.2355 -199.4148 0.1793 43.3\n"
"0.1000 -199.2282 -199.2782 0.0500 12.1\n"
"0.1200 -199.2135 -199.3017 0.0882 21.3\n"
"0.1400 -199.2060 -199.4014 0.1954 47.2\n"
"0.1600 -199.1878 -199.2201 0.0323 7.8\n"
"0.1800 -199.1630 -199.3306 0.1675 40.5\n"
"0.2000 -199.1496 -199.3506 0.2010 48.6\n",
dtype=float,
sep=" ",
)
assert np.isclose(logs, ref, rtol=1e-2, atol=1e-7).all()


def test_md_crystal_feas_log(
tmp_path: Path,
monkeypatch: MonkeyPatch,
Expand Down