class mchammer.observers.ClusterExpansionObserver(cluster_expansion, interval=None, tag='ClusterExpansionObserver')

This class represents a cluster expansion (CE) observer.

A CE observer allows to compute a property described by a CE along the trajectory sampled by a Monte Carlo (MC) simulation. In general this CE differs from the CE that is used to generate the trajectory. For example in a canonical MC simulation the latter would usually represent an energy (total or mixing energy) whereas the former CE(s) could map lattice constant or band gap.

  • cluster_expansion (icet.ClusterExpansion cluster expansion model) – to be used for observation
  • tag (str) – human readable observer name (default: ClusterExpansionObserver)
  • interval (int) – observation interval during the Monte Carlo simulation

str – name of observer


int – observation interval


Returns the value of the property from a cluster expansion model for a given atomic configuration.

Parameters:atoms (Atoms) – input atomic structure.
Return type:float

Data type of the observed data.

Return type:type