Calculators¶
ClusterExpansionCalculator¶

class
mchammer.calculators.
ClusterExpansionCalculator
(atoms, cluster_expansion, name='Cluster Expansion Calculator', scaling=None)¶ Cluster expansion calculator.
Class for efficiently calculating the cluster expansion property for a specific structure
Parameters:  atoms (ASE Atoms object) – the structure that the calculator can use to optimize the calculate functions.
 cluster_expansion (icet ClusterExpansion object) –
 name (str) – human readable identifier for this calculator
 scaling (float (default len(atoms))) – this scales the property that is gotten from cluster vector times ECIs. By default the cluster vector times ECIs is assumed to give property/atom and thus the default value is multiplied by number of atoms.
Todo
 add the real occupation constraints when that is setup in the cluster space.

atoms
¶ ASE Atoms object.

calculate_local_contribution
(local_indices=None, occupations=None)¶ Returns the sum of the contributions from the indices in the input list. local_indices refers to the lattice sites from which the local contributions should be summed up from. Occupations is the entire occupation vector.
Parameters:  local_indices (list of int) – the lattice indices for which to obtain the local contribution
 occupations (list of int) – the entire occupation vector
Returns: Return type: sum of contributions
Return type:

calculate_total
(*, occupations)¶ Calculates the total property of the current configuration.
Parameters: occupations (list of int) – the entire occupation vector (i.e. list of atomic species) Returns: Return type: total value of the property Return type: float

cluster_expansion
¶ icet ClusterExpansion object.

occupation_constraints
¶ A map from site to allowed species.

update_occupations
(indices, elements)¶ Set elements on the atoms object.
Parameters:  indices (list of int) – The list refer to indice on the lattice.
 elements (list of int) – The elements to put on the corresponding lattice site.