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from pytest import approx, fixture
from ase import Atoms
from ase.build import bulk
from ase.vibrations.raman import StaticRamanCalculator
from ase.vibrations.raman import StaticRamanPhononsCalculator
from ase.vibrations.placzek import PlaczekStatic
from ase.vibrations.placzek import PlaczekStaticPhonons
from ase.calculators.bond_polarizability import BondPolarizability
from ase.calculators.emt import EMT
@fixture(scope='module')
def Cbulk():
Cbulk = bulk('C', crystalstructure='fcc', a=2 * 1.221791471)
Cbulk = Cbulk.repeat([2, 1, 1])
Cbulk.calc = EMT()
return Cbulk
def test_bulk(Cbulk):
"""Bulk FCC carbon (for EMT) self consistency"""
delta = 0.02
name = 'bp'
rm = StaticRamanCalculator(Cbulk, BondPolarizability, name=name,
delta=delta)
rm.run()
pz = PlaczekStatic(Cbulk, name=name)
e_vib = pz.get_energies()
i_vib = pz.get_absolute_intensities()
assert len(e_vib) == 6
pz.summary()
name = 'phbp'
rm = StaticRamanPhononsCalculator(Cbulk, BondPolarizability,
calc=EMT(),
name=name,
delta=delta, supercell=(1, 1, 1))
rm.run()
pz = PlaczekStaticPhonons(Cbulk, name=name)
e_phonons = pz.get_energies()
assert len(e_vib) == len(e_phonons)
assert e_vib[3:] == approx(e_phonons[3:], 1)
i_phonons = pz.get_absolute_intensities()
assert i_vib[3:] == approx(i_phonons[3:], 1)
pz.summary()
def test_bulk_kpts(Cbulk):
"""Bulk FCC carbon (for EMT) for phonons"""
name = 'phbp'
rm = StaticRamanPhononsCalculator(Cbulk, BondPolarizability,
calc=EMT(), name=name,
delta=0.05, supercell=(2, 1, 1))
rm.run()
pz = PlaczekStaticPhonons(Cbulk, name=name, supercell=(2, 1, 1))
energies_1kpt = pz.get_energies()
pz.kpts = (2, 1, 1)
energies_2kpts = pz.get_energies()
assert len(energies_2kpts) == 2 * len(energies_1kpt)
pz.kpts = (2, 1, 2)
pz.summary()
def test_c3():
"""Can we calculate triangular (EMT groundstate) C3?"""
y, z = 0.30646191, 1.14411339 # emt relaxed
atoms = Atoms('C3', positions=[[0, 0, 0], [0, y, z], [0, z, y]])
atoms.calc = EMT()
name = 'bp'
rm = StaticRamanCalculator(atoms, BondPolarizability,
name=name, exname=name, txt='-')
rm.run()
pz = PlaczekStatic(atoms, name=name)
i_vib = pz.get_absolute_intensities()
assert i_vib[-3:] == approx([5.36301901, 5.36680555, 35.7323934], 1e-6)
pz.summary()
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