Source code for

# -*- coding: utf-8 -*-
# Copyright (c), The AiiDA team. All rights reserved.                     #
# This file is part of the AiiDA code.                                    #
#                                                                         #
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# For further information on the license, see the LICENSE.txt file        #
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Module of the KpointsData class, defining the AiiDA data type for storing
lists and meshes of k-points (i.e., points in the reciprocal space of a
periodic crystal structure).
import numpy

from .array import ArrayData

__all__ = ('KpointsData',)


[docs]class KpointsData(ArrayData): """ Class to handle array of kpoints in the Brillouin zone. Provide methods to generate either user-defined k-points or path of k-points along symmetry lines. Internally, all k-points are defined in terms of crystal (fractional) coordinates. Cell and lattice vector coordinates are in Angstroms, reciprocal lattice vectors in Angstrom^-1 . :note: The methods setting and using the Bravais lattice info assume the PRIMITIVE unit cell is provided in input to the set_cell or set_cell_from_structure methods. """
[docs] def get_description(self): """ Returns a string with infos retrieved from kpoints node's properties. :param node: :return: retstr """ try: mesh = self.get_kpoints_mesh() return 'Kpoints mesh: {}x{}x{} (+{:.1f},{:.1f},{:.1f})'.format( mesh[0][0], mesh[0][1], mesh[0][2], mesh[1][0], mesh[1][1], mesh[1][2] ) except AttributeError: try: return f'(Path of {len(self.get_kpoints())} kpts)' except OSError: return self.node_type
@property def cell(self): """ The crystal unit cell. Rows are the crystal vectors in Angstroms. :return: a 3x3 numpy.array """ return numpy.array(self.base.attributes.get('cell')) @cell.setter def cell(self, value): """ Set the crystal unit cell :param value: a 3x3 list/tuple/array of numbers (units = Angstroms). """ self._set_cell(value)
[docs] def _set_cell(self, value): """ Validate if 'value' is a allowed crystal unit cell :param value: something compatible with a 3x3 tuple of floats """ from aiida.common.exceptions import ModificationNotAllowed from import _get_valid_cell if self.is_stored: raise ModificationNotAllowed('KpointsData cannot be modified, it has already been stored') the_cell = _get_valid_cell(value) self.base.attributes.set('cell', the_cell)
@property def pbc(self): """ The periodic boundary conditions along the vectors a1,a2,a3. :return: a tuple of three booleans, each one tells if there are periodic boundary conditions for the i-th real-space direction (i=1,2,3) """ # return copy.deepcopy(self._pbc) return (self.base.attributes.get('pbc1'), self.base.attributes.get('pbc2'), self.base.attributes.get('pbc3')) @pbc.setter def pbc(self, value): """ Set the value of pbc, i.e. a tuple of three booleans, indicating if the cell is periodic in the 1,2,3 crystal direction """ self._set_pbc(value)
[docs] def _set_pbc(self, value): """ validate the pbc, then store them """ from aiida.common.exceptions import ModificationNotAllowed from import get_valid_pbc if self.is_stored: raise ModificationNotAllowed('The KpointsData object cannot be modified, it has already been stored') the_pbc = get_valid_pbc(value) self.base.attributes.set('pbc1', the_pbc[0]) self.base.attributes.set('pbc2', the_pbc[1]) self.base.attributes.set('pbc3', the_pbc[2])
@property def labels(self): """ Labels associated with the list of kpoints. List of tuples with kpoint index and kpoint name: ``[(0,'G'),(13,'M'),...]`` """ label_numbers = self.base.attributes.get('label_numbers', None) labels = self.base.attributes.get('labels', None) if labels is None or label_numbers is None: return None return list(zip(label_numbers, labels)) @labels.setter def labels(self, value): self._set_labels(value)
[docs] def _set_labels(self, value): """ set label names. Must pass in input a list like: ``[[0,'X'],[34,'L'],... ]`` """ # check if kpoints were set try: self.get_kpoints() except AttributeError: raise AttributeError('Kpoints must be set before the labels') if value is None: value = [] try: label_numbers = [int(i[0]) for i in value] except ValueError: raise ValueError('The input must contain an integer index, to map the labels into the kpoint list') labels = [str(i[1]) for i in value] if any(i > len(self.get_kpoints()) - 1 for i in label_numbers): raise ValueError('Index of label exceeding the list of kpoints') self.base.attributes.set('label_numbers', label_numbers) self.base.attributes.set('labels', labels)
[docs] def _change_reference(self, kpoints, to_cartesian=True): """ Change reference system, from cartesian to crystal coordinates (units of b1,b2,b3) or viceversa. :param kpoints: a list of (3) point coordinates :return kpoints: a list of (3) point coordinates in the new reference """ if not isinstance(kpoints, numpy.ndarray): raise ValueError('kpoints must be a numpy.array for method change_reference()') try: rec_cell = self.reciprocal_cell except AttributeError: # rec_cell = numpy.eye(3) raise AttributeError('Cannot use cartesian coordinates without having defined a cell') trec_cell = numpy.transpose(numpy.array(rec_cell)) if to_cartesian: matrix = trec_cell else: matrix = numpy.linalg.inv(trec_cell) # note: kpoints is a list Nx3, matrix is 3x3. # hence, first transpose kpoints, then multiply, finally transpose it back return numpy.transpose(, numpy.transpose(kpoints)))
[docs] def set_cell_from_structure(self, structuredata): """ Set a cell to be used for symmetry analysis from an AiiDA structure. Inherits both the cell and the pbc's. To set manually a cell, use "set_cell" :param structuredata: an instance of StructureData """ from aiida.orm import StructureData if not isinstance(structuredata, StructureData): raise ValueError( 'An instance of StructureData should be passed to ' 'the KpointsData, found instead {}'.format(structuredata.__class__) ) cell = structuredata.cell self.set_cell(cell, structuredata.pbc)
[docs] def set_cell(self, cell, pbc=None): """ Set a cell to be used for symmetry analysis. To set a cell from an AiiDA structure, use "set_cell_from_structure". :param cell: 3x3 matrix of cell vectors. Orientation: each row represent a lattice vector. Units are Angstroms. :param pbc: list of 3 booleans, True if in the nth crystal direction the structure is periodic. Default = [True,True,True] """ self.cell = cell if pbc is None: pbc = [True, True, True] self.pbc = pbc
@property def reciprocal_cell(self): """ Compute reciprocal cell from the internally set cell. :returns: reciprocal cell in units of 1/Angstrom with cell vectors stored as rows. Use e.g. reciprocal_cell[0] to access the first reciprocal cell vector. """ the_cell = numpy.array(self.cell) reciprocal_cell = 2. * numpy.pi * numpy.linalg.inv(the_cell).transpose() return reciprocal_cell
[docs] def set_kpoints_mesh(self, mesh, offset=None): """ Set KpointsData to represent a uniformily spaced mesh of kpoints in the Brillouin zone. This excludes the possibility of set/get kpoints :param mesh: a list of three integers, representing the size of the kpoint mesh along b1,b2,b3. :param offset: (optional) a list of three floats between 0 and 1. [0.,0.,0.] is Gamma centered mesh [0.5,0.5,0.5] is half shifted [1.,1.,1.] by periodicity should be equivalent to [0.,0.,0.] Default = [0.,0.,0.]. """ from aiida.common.exceptions import ModificationNotAllowed # validate try: the_mesh = [int(i) for i in mesh] if len(the_mesh) != 3: raise ValueError except (IndexError, ValueError, TypeError): raise ValueError('The kpoint mesh must be a list of three integers') if offset is None: offset = [0., 0., 0.] try: the_offset = [float(i) for i in offset] if len(the_offset) != 3: raise ValueError except (IndexError, ValueError, TypeError): raise ValueError('The offset must be a list of three floats') # check that there is no list of kpoints saved already # I cannot have both of them at the same time try: _ = self.get_array('kpoints') raise ModificationNotAllowed('KpointsData has already a kpoint-list stored') except KeyError: pass # store self.base.attributes.set('mesh', the_mesh) self.base.attributes.set('offset', the_offset)
[docs] def get_kpoints_mesh(self, print_list=False): """ Get the mesh of kpoints. :param print_list: default=False. If True, prints the mesh of kpoints as a list :raise AttributeError: if no mesh has been set :return mesh,offset: (if print_list=False) a list of 3 integers and a list of three floats 0<x<1, representing the mesh and the offset of kpoints :return kpoints: (if print_list = True) an explicit list of kpoints coordinates, similar to what returned by get_kpoints() """ mesh = self.base.attributes.get('mesh') offset = self.base.attributes.get('offset') if not print_list: return mesh, offset kpoints = numpy.mgrid[0:mesh[0], 0:mesh[1], 0:mesh[2]] kpoints = kpoints.reshape(3, -1).T offset_kpoints = kpoints + numpy.array(offset) offset_kpoints[:, 0] /= mesh[0] offset_kpoints[:, 1] /= mesh[1] offset_kpoints[:, 2] /= mesh[2] return offset_kpoints
[docs] def set_kpoints_mesh_from_density(self, distance, offset=None, force_parity=False): """ Set a kpoints mesh using a kpoints density, expressed as the maximum distance between adjacent points along a reciprocal axis :param distance: distance (in 1/Angstrom) between adjacent kpoints, i.e. the number of kpoints along each reciprocal axis i is :math:`|b_i|/distance` where :math:`|b_i|` is the norm of the reciprocal cell vector. :param offset: (optional) a list of three floats between 0 and 1. [0.,0.,0.] is Gamma centered mesh [0.5,0.5,0.5] is half shifted Default = [0.,0.,0.]. :param force_parity: (optional) if True, force each integer in the mesh to be even (except for the non-periodic directions). :note: a cell should be defined first. :note: the number of kpoints along non-periodic axes is always 1. """ if offset is None: offset = [0., 0., 0.] try: rec_cell = self.reciprocal_cell except AttributeError: # rec_cell = numpy.eye(3) raise AttributeError('Cannot define a mesh from a density without having defined a cell') # I first round to the fifth digit |b|/distance (to avoid that e.g. # 3.00000001 becomes 4) kpointsmesh = [ max(int(numpy.ceil(round(numpy.linalg.norm(b) / distance, 5))), 1) if pbc else 1 for pbc, b in zip(self.pbc, rec_cell) ] if force_parity: kpointsmesh = [k + (k % 2) if pbc else 1 for pbc, k in zip(self.pbc, kpointsmesh)] self.set_kpoints_mesh(kpointsmesh, offset=offset)
@property def _dimension(self): """ Dimensionality of the structure, found from its pbc (i.e. 1 if it's a 1D structure, 2 if its 2D, 3 if it's 3D ...). :return dimensionality: 0, 1, 2 or 3 :note: will return 3 if pbc has not been set beforehand """ try: return sum(self.pbc) except AttributeError: return 3
[docs] def _validate_kpoints_weights(self, kpoints, weights): """ Validate the list of kpoints and of weights before storage. Kpoints and weights must be convertible respectively to an array of N x dimension and N floats """ kpoints = numpy.array(kpoints) # I cannot just use `if not kpoints` because it's a numpy array and # `not` of a numpy array does not work if len(kpoints) == 0: # pylint: disable=len-as-condition if self._dimension == 0: # replace empty list by Gamma point kpoints = numpy.array([[0., 0., 0.]]) else: raise ValueError( 'empty kpoints list is valid only in zero dimension' '; instead here with have {} dimensions' ''.format(self._dimension) ) if len(kpoints.shape) <= 1: # list of scalars is accepted only in the 0D and 1D cases if self._dimension <= 1: # replace by singletons kpoints = kpoints.reshape(kpoints.shape[0], 1) else: raise ValueError(f'kpoints must be a list of lists in {self._dimension}D case') if kpoints.dtype != numpy.dtype(float): raise ValueError(f'kpoints must be an array of type floats. Found instead {kpoints.dtype}') if kpoints.shape[1] < self._dimension: raise ValueError( 'In a system which has {0} dimensions, kpoint need' 'more than {0} coordinates (found instead {1})'.format(self._dimension, kpoints.shape[1]) ) if weights is not None: weights = numpy.array(weights) if weights.shape[0] != kpoints.shape[0]: raise ValueError(f'Found {weights.shape[0]} weights but {kpoints.shape[0]} kpoints') if weights.dtype != numpy.dtype(float): raise ValueError(f'weights must be an array of type floats. Found instead {weights.dtype}') return kpoints, weights
[docs] def set_kpoints(self, kpoints, cartesian=False, labels=None, weights=None, fill_values=0): """ Set the list of kpoints. If a mesh has already been stored, raise a ModificationNotAllowed :param kpoints: a list of kpoints, each kpoint being a list of one, two or three coordinates, depending on self.pbc: if structure is 1D (only one True in self.pbc) one allows singletons or scalars for each k-point, if it's 2D it can be a length-2 list, and in all cases it can be a length-3 list. Examples: * [[0.,0.,0.],[0.1,0.1,0.1],...] for 1D, 2D or 3D * [[0.,0.],[0.1,0.1,],...] for 1D or 2D * [[0.],[0.1],...] for 1D * [0., 0.1, ...] for 1D (list of scalars) For 0D (all pbc are False), the list can be any of the above or empty - then only Gamma point is set. The value of k for the non-periodic dimension(s) is set by fill_values :param cartesian: if True, the coordinates given in input are treated as in cartesian units. If False, the coordinates are crystal, i.e. in units of b1,b2,b3. Default = False :param labels: optional, the list of labels to be set for some of the kpoints. See labels for more info :param weights: optional, a list of floats with the weight associated to the kpoint list :param fill_values: scalar to be set to all non-periodic dimensions (indicated by False in self.pbc), or list of values for each of the non-periodic dimensions. """ from aiida.common.exceptions import ModificationNotAllowed # check that it is a 'dim'x #kpoints dimensional array the_kpoints, the_weights = self._validate_kpoints_weights(kpoints, weights) # if k-points have less than 3 coordinates (low dimensionality), fill # with constant values the non-periodic dimensions if the_kpoints.shape[1] < 3: if numpy.isscalar(fill_values): # replace scalar by a list of 3-the_kpoints.shape[1] identical # elements fill_values = [fill_values] * (3 - the_kpoints.shape[1]) if len(fill_values) < 3 - the_kpoints.shape[1]: raise ValueError(f'fill_values should be either a scalar or a length-{3 - the_kpoints.shape[1]} list') else: tmp_kpoints = numpy.zeros((the_kpoints.shape[0], 0)) i_kpts = 0 i_fill = 0 for idim in range(3): # check periodic boundary condition of each of the 3 dimensions: # - if it's a periodic one, fill with the k-points values # defined in input # - if it's non-periodic, fill with one of the values in # fill_values if self.pbc[idim]: tmp_kpoints = numpy.hstack( (tmp_kpoints, the_kpoints[:, i_kpts].reshape((the_kpoints.shape[0], 1))) ) i_kpts += 1 else: tmp_kpoints = numpy.hstack( (tmp_kpoints, numpy.ones((the_kpoints.shape[0], 1)) * fill_values[i_fill]) ) i_fill += 1 the_kpoints = tmp_kpoints # change reference and always store in crystal coords if cartesian: the_kpoints = self._change_reference(the_kpoints, to_cartesian=False) # check that we did not saved a mesh already if self.base.attributes.get('mesh', None) is not None: raise ModificationNotAllowed('KpointsData has already a mesh stored') # store self.set_array('kpoints', the_kpoints) if the_weights is not None: self.set_array('weights', the_weights) if labels is not None: self.labels = labels
[docs] def get_kpoints(self, also_weights=False, cartesian=False): """ Return the list of kpoints :param also_weights: if True, returns also the list of weights. Default = False :param cartesian: if True, returns points in cartesian coordinates, otherwise, returns in crystal coordinates. Default = False. """ try: kpoints = numpy.array(self.get_array('kpoints')) except KeyError: raise AttributeError('Before the get, first set a list of kpoints') if cartesian: kpoints = self._change_reference(kpoints, to_cartesian=True) if also_weights: try: the_weights = self.get_array('weights') except KeyError: raise AttributeError('No weights were set') weights = numpy.array(the_weights) return kpoints, weights return kpoints