def get_bandstructure(self):
phonopy_obj = self.phonopy_obj
frequency_unit_factor = VaspToTHz
is_eigenvectors = False
unit_cell = phonopy_obj.unitcell.get_cell()
sym_tol = phonopy_obj.symmetry.tolerance
if self.band_conf is not None:
parameters = read_kpath(self.band_conf)
else:
parameters = generate_kpath_ase(unit_cell, sym_tol)
if not parameters:
return None, None, None
# Distances calculated in phonopy.band_structure.BandStructure object
# are based on absolute positions of q-points in reciprocal space
# as calculated by using the cell which is handed over during instantiation.
# Fooling that object by handing over a "unit cell" diag(1,1,1) instead clashes
# with calculation of non-analytical terms.
# Hence generate appropriate distances and special k-points list based on fractional
# coordinates in reciprocal space (to keep backwards compatibility with previous
# FHI-aims phonon implementation).
bands = []
bands_distances = []
distance = 0.0
bands_special_points = [distance]
bands_labels = []
label = parameters[0]["startname"]
for b in parameters:
kstart = np.array(b["kstart"])
kend = np.array(b["kend"])
npoints = b["npoints"]
dk = (kend - kstart) / (npoints - 1)
bands.append([(kstart + dk * n) for n in range(npoints)])
dk_length = np.linalg.norm(dk)
for n in range(npoints):
bands_distances.append(distance + dk_length * n)
distance += dk_length * (npoints - 1)
bands_special_points.append(distance)
label = [b["startname"], b["endname"]]
bands_labels.append(label)
bs_obj = BandStructure(bands,
phonopy_obj.dynamical_matrix,
with_eigenvectors=is_eigenvectors,
factor=frequency_unit_factor)
freqs = bs_obj.get_frequencies()
return np.array(freqs), np.array(bands), np.array(bands_labels)
