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def test_emt():
import numpy as np
from ase.calculators.emt import EMT
from ase import Atoms
a = 3.60
b = a / 2
cu = Atoms('Cu',
positions=[(0, 0, 0)],
cell=[(0, b, b),
(b, 0, b),
(b, b, 0)],
pbc=1,
calculator=EMT())
e0 = cu.get_potential_energy()
print(e0)
cu.set_cell(cu.get_cell() * 1.001, scale_atoms=True)
e1 = cu.get_potential_energy()
V = a**3 / 4
B = 2 * (e1 - e0) / 0.003**2 / V * 160.2
print(B)
for i in range(4):
x = 0.001 * i
A = np.array([(x, b, b+x),
(b, 0, b),
(b, b, 0)])
cu.set_cell(A, scale_atoms=True)
e = cu.get_potential_energy() - e0
if i == 0:
print(i, e)
else:
print(i, e, e / x**2)
A = np.array([(0, b, b),
(b, 0, b),
(6*b, 6*b, 0)])
R = np.zeros((2, 3))
for i in range(1, 2):
R[i] = i * A[2] / 6
print((Atoms('Cu2', positions=R,
pbc=1, cell=A,
calculator=EMT()).get_potential_energy() - 2 * e0) / 2)
A = np.array([(0, b, b),
(b, 0, b),
(10*b, 10*b, 0)])
R = np.zeros((3, 3))
for i in range(1, 3):
R[i] = i * A[2] / 10
print((Atoms('Cu3', positions=R,
pbc=1, cell=A,
calculator=EMT()).get_potential_energy() - 3 * e0) / 2)
A = np.array([(0, b, b),
(b, 0, b),
(b, b, 0)])
R = np.zeros((3, 3))
for i in range(1, 3):
R[i] = i * A[2]
print((Atoms('Cu3', positions=R,
pbc=(1, 1, 0), cell=A,
calculator=EMT()).get_potential_energy() - 3 * e0) / 2)
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