1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
def test_counterions():
""" Test AtomicCounterIon is force/energy consistent over
PBCs and with cutoff """
import numpy as np
from ase import Atoms
from ase import units
from ase.calculators.counterions import AtomicCounterIon as ACI
sigma = 1.868 * (1.0/2.0)**(1.0/6.0)
epsilon = 0.00277 * units.kcal / units.mol
atoms = Atoms('3Na', positions=np.array([[0, 0, -2], [0,0,0], [0,0,2]]))
atoms.cell = [10, 10, 10]
atoms.pbc = True
atoms.calc = ACI(1, epsilon, sigma, rc=4.5)
points = np.arange(-15., 15., 0.2)
for p in points:
f = atoms.get_forces()
fn = atoms.calc.calculate_numerical_forces(atoms, 1e-5)
df = (f-fn)
assert abs(df).max() < 1e-8
|
