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import numpy as np
from ase import Atoms
from ase.calculators.calculator import compare_atoms
def test_compare_atoms():
"""
Check that Atoms.compare_atoms correctly accounts for the different
types of system changes
"""
# A system property that's an attribute of Atoms, but isn't in
# Atoms.arrays (currently this is just 'cell' and 'pbc')
cell1 = np.array([[1, 0, 0], [0, 1, 0], [0, 0, 1]])
cell2 = cell1 * 2
atoms1 = Atoms(cell=cell1)
atoms2 = Atoms(cell=cell2)
assert set(compare_atoms(atoms1, atoms2)) == {"cell"}
# A system property other than 'initial_charges' or 'initial_magmoms'
# that exists in the `arrays` attribute of one Atoms object but not the
# other
atoms1 = Atoms()
atoms2 = Atoms(numbers=[0], positions=[[0, 0, 0]])
assert set(compare_atoms(atoms1, atoms2)) == {"positions", "numbers"}
# A change in a system property that exists in the `arrays` attribute
# of both Atoms objects passed into this function
atoms1 = Atoms(numbers=[0], positions=[[0, 0, 0]])
atoms2 = Atoms(numbers=[0], positions=[[1, 0, 0]])
assert set(compare_atoms(atoms1, atoms2)) == {"positions"}
# An excluded property (re-use atoms1 and atoms2 from previous check)
assert set(compare_atoms(atoms1, atoms2,
excluded_properties={"positions"})) == set()
# Optional array (currently 'initial_charges' or 'initial_magmoms')
# NOTE: Suppose you initialize an array of *zero charges* for atoms2
# but not atoms1. The current compare_atoms function will still
# indicate that 'initial_charges' is in system_changes simply
# because it isn't in both of them. This is despite the fact that
# if one were to call atoms1.get_initial_charges, you would get
# back an array of zeros. However, this scenario should only ever
# occur rarely.
atoms1 = Atoms(numbers=[0], positions=[[0, 0, 0]])
atoms2 = Atoms(numbers=[0], positions=[[0, 0, 0]], charges=[1.13])
assert set(compare_atoms(atoms1, atoms2)) == {"initial_charges"}
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