Source code for clease.montecarlo.constraints.pair_constraint

from clease.datastructures import SystemChanges
from .mc_constraint import MCConstraint

[docs]class PairConstraint(MCConstraint): """ Pair constraint is a constraint that prevents two species from being part of a pair cluster Parameters: elements: list List of symbols (e.g. [Al, X] or [X, X]) pair_cluster: Cluster Instance of a the Cluster class. An instance of a cluster class can for instance be obtained from a ClusterExpansionSettings object via settings.cluster_list.get_by_name("c2_d000_0")[0] trans_matrix: list of dicts Translation matrix for indices. This can be obtained from the trans_matrix attribute of the ClusterExpansionSettings object atoms: Atoms object Atoms object used for MC calculations """ def __init__(self, elements, pair_cluster, trans_matrix, atoms): self.elements = sorted(elements) self.pair_cluster = pair_cluster self.trans_mat = trans_matrix self.atoms = atoms def _check_one(self, idx): t_indx = self.trans_mat[idx] for figure in self.pair_cluster.indices: symbs = sorted([self.atoms[t_indx[j]].symbol for j in figure]) if self.elements == symbs: return False return True def __call__(self, system_changes: SystemChanges): # Introduce all changes for change in system_changes: self.atoms[change.index].symbol = change.new_symb # Loop through all changes move_ok = True for change in system_changes: if not self._check_one(change.index): move_ok = False break # Undo all changes for change in system_changes: self.atoms[change.index].symbol = change.old_symb return move_ok