1def test_aic():
2    """Test Atomic Counter Ion calc forces."""
3    import numpy as np
4    from ase import Atoms
5    from ase.calculators.counterions import AtomicCounterIon as ACI
6
7    atoms = Atoms('2Na', positions=np.array([[0, 0, 0], [0, 0, 4]]))
8
9    atoms.calc = ACI(1, 1.6642, 0.0001201186, rc=4.5)
10    f = atoms.get_forces()
11    df = atoms.calc.calculate_numerical_forces(atoms, 1e-6) - f
12    print(df)
13    assert abs(df).max() < 2e-6
14