Chimie Théorique » QMX

import numpy as np

from ase import Atoms

from ase.units import fs

from ase.calculators.test import TestPotential

from ase.calculators.emt import EMT

from ase.md import VelocityVerlet

from ase.io import PickleTrajectory, read

from ase.optimize import QuasiNewton

np.seterr(all='raise')

a = Atoms('4X',

          masses=[1, 2, 3, 4],

          positions=[(0, 0, 0),

                     (1, 0, 0),

                     (0, 1, 0),

                     (0.1, 0.2, 0.7)],

          calculator=TestPotential())

print a.get_forces()

md = VelocityVerlet(a, dt=0.5 * fs, logfile='-', loginterval=500)

traj = PickleTrajectory('4N.traj', 'w', a)

md.attach(traj.write, 100)

e0 = a.get_total_energy()

md.run(steps=10000)

del traj

assert abs(read('4N.traj').get_total_energy() - e0) < 0.0001

qn = QuasiNewton(a)

qn.run(0.001)

assert abs(a.get_potential_energy() - 1.0) < 0.000002