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# fmt: off
import pytest
from ase import units
from ase.build import bulk
from ase.calculators.emt import EMT
from ase.io import Trajectory
from ase.md import VelocityVerlet
from ase.md.velocitydistribution import MaxwellBoltzmannDistribution
@pytest.fixture(name="atoms")
def fixture_atoms():
atoms = bulk("Au") * 2
MaxwellBoltzmannDistribution(atoms, temperature_K=100.0)
atoms.calc = EMT()
return atoms
def test_md(atoms, testdir):
def f():
print(atoms.get_potential_energy(), atoms.get_total_energy())
with VelocityVerlet(atoms, timestep=0.1) as md:
md.attach(f)
with Trajectory('Cu2.traj', 'w', atoms) as traj:
md.attach(traj.write, interval=3)
md.run(steps=20)
with Trajectory('Cu2.traj', 'r') as traj:
traj[-1]
# Really?? No assertion at all?
@pytest.mark.parametrize("md_class", [VelocityVerlet])
def test_run_twice(md_class, atoms):
"""Test if `steps` increments `max_steps` when `run` is called twice."""
steps = 5
with md_class(atoms, timestep=1.0 * units.fs) as md:
md.run(steps=steps)
md.run(steps=steps)
assert md.nsteps == 2 * steps
assert md.max_steps == 2 * steps
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