def test_energy_forces_stress():
"""
To test that the calculator can produce correct energy and forces. This
is done by comparing the energy for an FCC argon lattice with an example
model to the known value; the forces/stress returned by the model are
compared to numerical estimates via finite difference.
"""
import numpy as np
from pytest import importorskip
importorskip('kimpy')
from ase.calculators.kim import KIM
from ase.lattice.cubic import FaceCenteredCubic
# Create an FCC atoms crystal
atoms = FaceCenteredCubic(
directions=[[1, 0, 0], [0, 1, 0], [0, 0, 1]],
size=(1, 1, 1),
symbol="Ar",
pbc=(1, 0, 0),
latticeconstant=3.0,
)
# Perturb the x coordinate of the first atom by less than the cutoff distance
atoms.positions[0, 0] += 0.01
calc = KIM("ex_model_Ar_P_Morse_07C")
atoms.set_calculator(calc)
# Get energy and analytical forces/stress from KIM model
energy = atoms.get_potential_energy()
forces = atoms.get_forces()
stress = atoms.get_stress()
# Previously computed energy for this configuration for this model
energy_ref = 19.7196709065 # eV
# Compute forces and virial stress numerically
forces_numer = calc.calculate_numerical_forces(atoms, d=0.0001)
stress_numer = calc.calculate_numerical_stress(atoms, d=0.0001, voigt=True)
tol = 1e-6
assert np.isclose(energy, energy_ref, tol)
assert np.allclose(forces, forces_numer, tol)
assert np.allclose(stress, stress_numer, tol)
# This has been known to segfault
atoms.set_pbc(True)
atoms.get_potential_energy()
def test_multi_neighlist():
"""
To test that the correct energy/forces/stress can be computed using a
model that implements multiple cutoffs. This is done by construct a 10
Angstrom x 10 Angstrom x 10 Angstrom non-periodic cell filled with 15
randomly positioned atoms and requesting tha tthe model compute the
energy, forces, and virial stress. The energy returned by the model is
compared to a known precomputed value, while the forces and stress
returned are compared to numerical estimates via finite difference.
"""
import numpy as np
from ase import Atoms
from pytest import importorskip
importorskip('kimpy')
from ase.calculators.kim import KIM
# Create random cluster of atoms
positions = np.random.RandomState(34).rand(15, 3) * 10
atoms = Atoms(
"Ar" * 15, positions=positions, pbc=False, cell=[[10, 0, 0], [0, 10, 0], [0, 0, 10]]
)
calc = KIM("ex_model_Ar_P_Morse_MultiCutoff")
atoms.set_calculator(calc)
# Get energy and analytical forces/stress from KIM Model
energy = atoms.get_potential_energy()
forces = atoms.get_forces()
stress = atoms.get_stress()
# Previously computed energy for this configuration for this model
energy_ref = 34.69963483186903 # eV
# Compute forces and virial stress numerically
forces_numer = calc.calculate_numerical_forces(atoms, d=0.0001)
stress_numer = calc.calculate_numerical_stress(atoms, d=0.0001, voigt=True)
tol = 1e-6
assert np.isclose(energy, energy_ref, tol)
assert np.allclose(forces, forces_numer, tol)
assert np.allclose(stress, stress_numer, tol)
pbc=(1, 0, 0),
latticeconstant=3.0,
)
# Perturb the x coordinate of the first atom by less than the cutoff distance
atoms.positions[0, 0] += 0.01
calc = KIM("ex_model_Ar_P_Morse_07C")
atoms.set_calculator(calc)
# Get energy and analytical forces/stress from KIM model
energy = atoms.get_potential_energy()
forces = atoms.get_forces()
stress = atoms.get_stress()
# Previously computed energy for this configuration for this model
energy_ref = 19.7196709065 # eV
# Compute forces and virial stress numerically
forces_numer = calc.calculate_numerical_forces(atoms, d=0.0001)
stress_numer = calc.calculate_numerical_stress(atoms, d=0.0001, voigt=True)
tol = 1e-6
assert np.isclose(energy, energy_ref, tol)
assert np.allclose(forces, forces_numer, tol)
assert np.allclose(stress, stress_numer, tol)
# This has been known to segfault
atoms.set_pbc(True)
atoms.get_potential_energy()
