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import numpy as np
from numpy.testing import assert_allclose
import pytest
from ase.build import bulk
from ase.constraints import ExpCellFilter
from ase.optimize import BFGS
@pytest.mark.calculator_lite
@pytest.mark.calculator('lammpsrun')
def test_Pt_stress_cellopt(factory, pt_eam_potential_file):
params = {}
params['pair_style'] = 'eam'
params['pair_coeff'] = ['1 1 {}'.format(pt_eam_potential_file)]
# XXX Should it accept Path objects? Yes definitely for files.
with factory.calc(specorder=['Pt'], files=[str(pt_eam_potential_file)],
**params) as calc:
rng = np.random.RandomState(17)
atoms = bulk('Pt') * (2, 2, 2)
atoms.rattle(stdev=0.1)
atoms.cell += 2 * rng.rand(3, 3)
atoms.calc = calc
assert_allclose(atoms.get_stress(), calc.calculate_numerical_stress(atoms),
atol=1e-4, rtol=1e-4)
opt = BFGS(ExpCellFilter(atoms))
for i, _ in enumerate(opt.irun(fmax=0.001)):
pass
cell1_ref = np.array(
[[0.16524, 3.8999, 3.92855],
[4.211015, 0.634928, 5.047811],
[4.429529, 3.293805, 0.447377]]
)
assert_allclose(np.asarray(atoms.cell), cell1_ref, atol=3e-4, rtol=3e-4)
assert_allclose(atoms.get_stress(), calc.calculate_numerical_stress(atoms),
atol=1e-4, rtol=1e-4)
assert i < 80, 'Expected 59 iterations, got many more: {}'.format(i)
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