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def test_bandstructure_transform_mcl():
# Test that bandpath() correctly transforms the band path from
# reference (canonical) cell to actual cell provided by user.
import numpy as np
from ase import Atoms
from ase.utils import workdir
from ase.spectrum.band_structure import calculate_band_structure
from ase.calculators.test import FreeElectrons
from ase.cell import Cell
def _atoms(cell):
atoms = Atoms(cell=cell, pbc=True)
atoms.calc = FreeElectrons()
return atoms
# MCL with beta > 90, which is a common convention -- but ours is
# alpha < 90. We want the bandpath returned by that cell to yield the
# exact same band structure as our own (alpha < 90) version of the
# same cell.
cell = Cell.new([3., 5., 4., 90., 110., 90.])
lat = cell.get_bravais_lattice()
density = 10.0
cell0 = lat.tocell()
path0 = lat.bandpath(density=density)
print(cell.cellpar().round(3))
print(cell0.cellpar().round(3))
with workdir('files', mkdir=True):
bs = calculate_band_structure(_atoms(cell),
cell.bandpath(density=density))
bs.write('bs.json')
# bs.plot(emin=0, emax=20, filename='fig.bs.svg')
bs0 = calculate_band_structure(_atoms(cell0), path0)
bs0.write('bs0.json')
# bs0.plot(emin=0, emax=20, filename='fig.bs0.svg')
maxerr = np.abs(bs.energies - bs0.energies).max()
assert maxerr < 1e-12, maxerr
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