bands.append(band) unitcell = read_vasp("POSCAR") phonon = Phonopy(unitcell, [[2, 0, 0], [0, 2, 0], [0, 0, 2]], primitive_matrix=[[0, 0.5, 0.5], [0.5, 0, 0.5], [0.5, 0.5, 0]]) force_sets = parse_FORCE_SETS() phonon.set_displacement_dataset(force_sets) phonon.produce_force_constants() primitive = phonon.get_primitive() nac_params = parse_BORN(primitive, filename="BORN") phonon.set_nac_params(nac_params) phonon.set_group_velocity() bands = [] append_band(bands, [0.0, 0.0, 0.0], [0.5, 0.0, 0.0]) append_band(bands, [0.5, 0.0, 0.0], [0.5, 0.5, 0.0]) append_band(bands, [0.5, 0.5, 0.0], [0.0, 0.0, 0.0]) append_band(bands, [0.0, 0.0, 0.0], [0.5, 0.5, 0.5]) phonon.set_band_structure(bands) q_points, distances, frequencies, eigvecs = phonon.get_band_structure() group_velocities = phonon.get_group_velocities_on_bands() print(len(frequencies)) print(frequencies[0].shape) print(len(group_velocities)) print(group_velocities[0].shape)