def _log_band_structure_information(band_structure: BandStructure):
log_banner("BAND STRUCTURE")
info = [
"# bands: {}".format(band_structure.nb_bands),
"# k-points: {}".format(len(band_structure.kpoints)),
"Fermi level: {:.3f} eV".format(band_structure.efermi),
"spin polarized: {}".format(band_structure.is_spin_polarized),
"metallic: {}".format(band_structure.is_metal()),
]
logger.info("Input band structure information:")
log_list(info)
if band_structure.is_metal():
return
logger.info("Band gap:")
band_gap_info = []
bg_data = band_structure.get_band_gap()
if not bg_data["direct"]:
band_gap_info.append("indirect band gap: {:.3f} eV".format(
bg_data["energy"]))
direct_data = band_structure.get_direct_band_gap_dict()
direct_bg = min((spin_data["value"] for spin_data in direct_data.values()))
band_gap_info.append("direct band gap: {:.3f} eV".format(direct_bg))
direct_kpoint = []
for spin, spin_data in direct_data.items():
direct_kindex = spin_data["kpoint_index"]
kpt_str = _kpt_str.format(
k=band_structure.kpoints[direct_kindex].frac_coords)
direct_kpoint.append(kpt_str)
band_gap_info.append("direct k-point: {}".format(", ".join(direct_kpoint)))
log_list(band_gap_info)
vbm_data = band_structure.get_vbm()
cbm_data = band_structure.get_cbm()
logger.info("Valence band maximum:")
_log_band_edge_information(band_structure, vbm_data)
logger.info("Conduction band minimum:")
_log_band_edge_information(band_structure, cbm_data)
def get_energy_cutoffs(
energy_cutoff: float, band_structure: BandStructure
) -> Tuple[float, float]:
if energy_cutoff and band_structure.is_metal():
min_e = band_structure.efermi - energy_cutoff
max_e = band_structure.efermi + energy_cutoff
elif energy_cutoff:
min_e = band_structure.get_vbm()["energy"] - energy_cutoff
max_e = band_structure.get_cbm()["energy"] + energy_cutoff
else:
min_e = min(
[band_structure.bands[spin].min() for spin in band_structure.bands.keys()]
)
max_e = max(
[band_structure.bands[spin].max() for spin in band_structure.bands.keys()]
)
return min_e, max_e
def get_vb_idx(energy_cutoff: float, band_structure: BandStructure):
if band_structure.is_metal():
return None
ibands = get_ibands(energy_cutoff, band_structure, return_idx=False)
new_vb_idx = {}
for spin, bands in band_structure.bands.items():
spin_ibands = ibands[spin]
# valence bands are all bands that contain energies less than efermi
vbs = (bands < band_structure.efermi).any(axis=1)
vb_idx = np.where(vbs)[0].max()
# need to know the index of the valence band after discounting
# bands during the interpolation. As ibands is just a list of
# True/False, we can count the number of Trues included up to
# and including the VBM to get the new number of valence bands
new_vb_idx[spin] = sum(spin_ibands[: vb_idx + 1]) - 1
return new_vb_idx
