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# fmt: off
import pytest
from ase.build import bulk
from ase.calculators.calculator import compare_atoms
from ase.calculators.emt import EMT
from ase.io.trajectory import Trajectory
from ase.optimize import BFGS
@pytest.fixture()
def atoms0():
atoms = bulk('Au', cubic=True)
atoms.rattle(stdev=0.15)
return atoms
@pytest.fixture()
def atoms(atoms0):
atoms = atoms0.copy()
atoms.calc = EMT()
return atoms
@pytest.mark.optimize()
def test_irun_start(atoms0, atoms):
opt = BFGS(atoms)
irun = opt.irun(fmax=0.0)
next(irun) # Initially it yields without yet having performed a step:
assert not compare_atoms(atoms0, atoms)
next(irun) # Now it must have performed a step:
assert compare_atoms(atoms0, atoms) == ['positions']
@pytest.mark.optimize()
def test_attach_trajectory(tmp_path, atoms0, atoms):
# Previously one needed to specify the same atoms object to
# both trajectory and optimizer, if trajectory was opened separately.
# This test ensures that doing so is no longer necessary.
#
# We also opportunistically test that the first image written to the
# trajectory is in fact the original atoms object.
trajfile = tmp_path / 'tmp.traj'
n_yields = 3
with Trajectory(trajfile, 'w') as traj:
opt = BFGS(atoms, trajectory=traj)
irun = opt.irun(fmax=0.0)
for _ in range(n_yields):
next(irun)
with Trajectory(tmp_path / 'tmp.traj') as traj:
images = list(traj)
# The number of images must be equal to the number of yielding.
assert len(images) == n_yields
assert not compare_atoms(atoms0, images[0])
assert compare_atoms(atoms0, images[-1]) == ['positions']
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