#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright 2019 Chris Sewell
#
# This file is part of aiida-crystal17.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms and conditions
# of version 3 of the GNU Lesser General Public License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
[docs]def create_kpoints_from_distance(structure, distance, force_parity=True):
"""
Generate a uniformly spaced kpoint mesh for a given structure where the spacing between kpoints in reciprocal
space is guaranteed to be at least the defined distance.
:param structure: the StructureData to which the mesh should apply
:param distance: a float with the desired distance between kpoints in reciprocal space
:param force_parity: a bool to specify whether the generated mesh should maintain parity
:returns: a KpointsData with the generated mesh
"""
from aiida.orm import KpointsData
from numpy import linalg
epsilon = 1e-5
kpoints = KpointsData()
kpoints.set_cell_from_structure(structure)
kpoints.set_kpoints_mesh_from_density(distance, force_parity=force_parity)
lengths_vector = [linalg.norm(vector) for vector in structure.cell]
lengths_kpoint = kpoints.get_kpoints_mesh()[0]
is_symmetric_cell = all(
abs(length - lengths_vector[0]) < epsilon for length in lengths_vector
)
is_symmetric_mesh = all(length == lengths_kpoint[0] for length in lengths_kpoint)
# If the vectors of the cell all have the same length, the kpoint mesh should be isotropic as well
if is_symmetric_cell and not is_symmetric_mesh:
nk = max(lengths_kpoint)
kpoints.set_kpoints_mesh([nk, nk, nk])
return kpoints