Monte Carlo Constraints
- class clease.montecarlo.constraints.CollectiveVariableConstraint(xmin=0.0, xmax=1.0, getter=None)[source]
Constraint that ensures that the collective variable defined by the getter stays within certain bounds
Parameters:
- xmin: float
Minimum value for the collective variable
- xmax: float
Maximum value for the collective variable
- getter: MCObserver
MCObsrever that support peak keyword that returns the collective variable after the proposed move
- class clease.montecarlo.constraints.ConstrainElementInserts(atoms, index_by_basis, element_by_basis)[source]
Constrain inserting the elements by basis. This constraint is intended to be used together with SGCMonteCarlo
- atoms: Atoms object
ASE Atoms object used in the MC simulation
- index_by_basis: list
Indices ordered by basis (same as index_by_basis parameter in ClusterExpansionSettings). If an Atoms object has 10 sites where the first 4 belongs to the first basis, the next 3 belongs to the next basis and the last 3 belongs to the last basis, the index_by_basis would be [[0, 1, 2, 3], [4, 5, 6], [7, 8, 9]]
- element_by_basis: list
List specifying which elements are allowed in each basis. If there are two basis where Si and O are allowed in the fist basis while Si and C are allowed in the second basis, the argument would be [[‘Si’, ‘O’], [‘Si’, ‘C’]]
- class clease.montecarlo.constraints.ConstrainSwapByBasis(atoms: Atoms, index_by_basis: Sequence[Sequence[int]])[source]
Constraint that restricts swaps of atoms within a given basis. This constraint is intended to be used together with canonical Monte Carlo calculations where the trial moves consist of swapping two atoms.
Parameters:
- atoms: Atoms object
ASE Atoms object used in the MC simulation
- index_by_basis: List[List[int]]
Indices ordered by basis (same as
index_by_basis
parameter in theClusterExpansionSettings
settings object.). If an Atoms object has 10 sites where the first 4 belongs to the first basis, the next 3 belongs to the next basis and the last 3 belongs to the last basis, theindex_by_basis
would be [[0, 1, 2, 3], [4, 5, 6], [7, 8, 9]].
Note: swaps are only allowed within each basis, not across two basis.
- class clease.montecarlo.constraints.FixedElement(element)[source]
Class for forcing an element of a certiain type to stay fixed.
Parameters:
- element: str
Name of the element that is supposed to stay fixed
- class clease.montecarlo.constraints.FixedIndices(fixed_indices: Sequence[int])[source]
Constrain a given set of indices during an MC run. Any suggested system changes by the MC algorithm are rejected if they invovle an index in the fixed indices.
Parameters:
- fixed_indices: sequence of integers
The indices of the atoms object which are to be fixed.
- class clease.montecarlo.constraints.MCConstraint[source]
Class for that prevents the MC sampler to run certain moves
- class clease.montecarlo.constraints.PairConstraint(elements, pair_cluster, trans_matrix, atoms)[source]
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