Subsequently, all clusters within a migration unit are found by enumerating all points, pairs, triplets, etc. via a cutoff radius (specified by the user) for each type of cluster. All symmetrically equivalent clusters are then grouped as orbits, which become elements in the "correlation vector" (see Sec. A). Clusters and orbits are coded into the kMCpy.model as the Cluster and the Orbit classes. In addition to the species and the atomic coordinates, Cluster and Orbit both have functions to compute "correlation" (see Sec. A) for a given orbit based on the occupation of sites.