Chimie Théorique » QMX

#!/usr/bin/python

"""

Run some VASP tests to ensure that the VASP calculator works. This

is conditional on the existence of the VASP_COMMAND or VASP_SCRIPT

environment variables

"""

from ase.test import NotAvailable

import os

vcmd = os.getenv('VASP_COMMAND')

vscr = os.getenv('VASP_SCRIPT')

if vcmd == None and vscr == None:

    raise NotAvailable('Neither VASP_COMMAND nor VASP_SCRIPT defined')

from ase import Atoms

from ase.calculators.vasp import Vasp

import numpy as np

def array_almost_equal(a1, a2, tol=np.finfo(type(1.0)).eps):

    """Replacement for old numpy.testing.utils.array_almost_equal."""

    return (np.abs(a1 - a2) < tol).all()

d = 1.14

co = Atoms('CO', positions=[(0, 0, 0), (0, 0, d)],

              pbc=True)

co.center(vacuum=5.)

calc = Vasp(

            xc = 'PBE',

            prec = 'Low',

            algo = 'Fast',

            ismear= 0,

            sigma = 1.,

            lwave = False,

            lcharg = False)

co.set_calculator(calc)

en = co.get_potential_energy()

assert abs(en + 14.918933) < 1e-4

# Secondly, check that restart from the previously created VASP output works

calc2 = Vasp(restart=True)

co2 = calc2.get_atoms()

# Need tolerance of 1e-14 because VASP itself changes coordinates

# slightly between reading POSCAR and writing CONTCAR even if no ionic

# steps are made.

assert array_almost_equal(co.positions, co2.positions, 1e-14)

assert en - co2.get_potential_energy() == 0.

assert array_almost_equal(calc.get_stress(co), calc2.get_stress(co2))

assert array_almost_equal(calc.get_forces(co), calc2.get_forces(co2))

assert array_almost_equal(calc.get_eigenvalues(), calc2.get_eigenvalues())

assert calc.get_number_of_bands() == calc2.get_number_of_bands()

assert calc.get_xc_functional() == calc2.get_xc_functional()