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import numpy as np
import pytest
from numpy.testing import assert_allclose
from ase.build import bulk
from ase.calculators.fd import calculate_numerical_stress
from ase.filters import FrechetCellFilter
from ase.optimize import BFGS
@pytest.fixture(name="atoms")
def fixture_atoms():
rng = np.random.RandomState(17)
atoms = bulk('Pt') * (2, 2, 2)
atoms.rattle(stdev=0.1)
atoms.cell += 2 * rng.random((3, 3))
return atoms
@pytest.mark.calculator_lite()
@pytest.mark.calculator('lammpslib')
def test_Pt_stress_cellopt(atoms, factory):
"""Test if the stresses and the optimized cell are as expected.
This test is taken from the one with the same name from lammpsrun.
"""
lmpcmds = ['pair_style eam', 'pair_coeff 1 1 Pt_u3.eam']
with factory.calc(lmpcmds=lmpcmds) as calc:
atoms.calc = calc
assert_allclose(atoms.get_stress(),
calculate_numerical_stress(atoms),
atol=1e-4, rtol=1e-4)
with BFGS(FrechetCellFilter(atoms)) as opt:
opt.run(fmax=0.001)
cell1_ref = np.array([
[0.178351, 3.885347, 3.942046],
[4.19978, 0.591071, 5.062568],
[4.449044, 3.264038, 0.471548],
])
assert_allclose(np.asarray(atoms.cell), cell1_ref,
atol=3e-4, rtol=3e-4)
assert_allclose(atoms.get_stress(),
calculate_numerical_stress(atoms),
atol=1e-4, rtol=1e-4)
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