httk.atomistic.cellshape module¶

class
httk.atomistic.cellshape.
CellShape
(niggli_matrix, orientation=1, basis=None)[source]¶ Bases:
httk.core.httkobject.HttkObject
Represents a cell (e.g., a unitcell, but also possibly just the basis vectors of a nonperiodic system)

basis
¶

classmethod
create
(cellshape=None, basis=None, metric=None, niggli_matrix=None, a=None, b=None, c=None, alpha=None, beta=None, gamma=None, lengths=None, angles=None, scale=None, scaling=None, volume=None, periodicity=None, nonperiodic_vecs=None, orientation=1)[source]¶ Create a new cell object,
cell: any one of the following:
 a 3x3 array with (in rows) the three basis vectors of the cell (a nonperiodic system should conventionally use an identity matrix)
 a dict with a single key ‘niggli_matrix’ with a 3x2 array with the Niggli Matrix representation of the cell
 a dict with 6 keys, ‘a’, ‘b’, ‘c’, ‘alpha’, ‘beta’, ‘gamma’ giving the cell parameters as floats
 scaling: free form input parsed for a scale.
 positive value = multiply basis vectors by this value negative value = rescale basis vectors so that cell volume becomes abs(value).
scale: set to nonNone to multiply all cell vectors with this factor
volume: set to nonNone if the basis vectors only give directions, and the volume of the cell should be this value (overrides scale)
 periodicity: free form input parsed for periodicity
 sequence: True/False for each basis vector being periodic integer: number of nonperiodic basis vectors
