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# fmt: off
import numpy as np
import pytest
from ase.build import fcc111
from ase.calculators.calculator import CalculatorSetupError
from ase.calculators.emt import EMT
from ase.calculators.mixing import (
AverageCalculator,
LinearCombinationCalculator,
MixedCalculator,
Mixer,
SumCalculator,
)
from ase.constraints import FixAtoms
def test_mixingcalc():
"""This test checks the basic functionality of the MixingCalculators.
The example system is based on the SinglePointCalculator test case.
"""
# Calculate reference values:
atoms = fcc111("Cu", (2, 2, 1), vacuum=10.0)
atoms[0].x += 0.2
# First run the test with EMT similarly to the test of the single point
# calculator.
calc = EMT()
atoms.calc = calc
forces = atoms.get_forces()
voigt_stress = atoms.get_stress()
stress_tensor = atoms.get_stress(voigt=False)
# Mixer: check that stresses of different shapes are handled correctly
stresses = [voigt_stress, stress_tensor]
reshape_stress = Mixer.make_stress_voigt(stresses)
assert np.isclose(reshape_stress[0], reshape_stress[1]).all()
# SumCalculator: Only one way to associate a calculator with an atoms
# object.
atoms1 = atoms.copy()
calc1 = SumCalculator([EMT(), EMT()])
atoms1.calc = calc1
# Check the results.
assert np.isclose(2 * forces, atoms1.get_forces()).all()
assert np.isclose(2 * voigt_stress, atoms1.get_stress()).all()
assert atoms1.get_stress().shape == (6,)
# testing step
atoms1[0].x += 0.2
assert not np.isclose(2 * forces, atoms1.get_forces()).all()
# Check constraints
atoms1.set_constraint(FixAtoms(indices=[atom.index for atom in atoms]))
assert np.isclose(0, atoms1.get_forces()).all()
# AverageCalculator:
atoms1 = atoms.copy()
calc1 = AverageCalculator([EMT(), EMT()])
atoms1.calc = calc1
# LinearCombinationCalculator:
atoms2 = atoms.copy()
calc2 = LinearCombinationCalculator([EMT(), EMT()], weights=[0.5, 0.5])
atoms2.calc = calc2
# Check the results (it should be the same because it is tha average of
# the same values).
assert np.isclose(forces, atoms1.get_forces()).all()
assert np.isclose(forces, atoms2.get_forces()).all()
# testing step
atoms1[0].x += 0.2
assert not np.isclose(2 * forces, atoms1.get_forces()).all()
with pytest.raises(CalculatorSetupError):
calc1 = LinearCombinationCalculator([], [])
with pytest.raises(CalculatorSetupError):
calc1 = AverageCalculator([])
# test MixedCalculator and energy contributions
w1, w2 = 0.78, 0.22
atoms1 = atoms.copy()
atoms1.calc = EMT()
E_tot = atoms1.get_potential_energy()
calc1 = MixedCalculator(EMT(), EMT(), w1, w2)
E1, E2 = calc1.get_energy_contributions(atoms1)
assert np.isclose(E1, E_tot)
assert np.isclose(E2, E_tot)
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