Ranking of atoms can be performed in ChemDASH by three separate methods: random, bond valence sum (BVS) and electrostatic potential. The BVS method is implemented such that the deviation of each atom from its ideal BVS (derived from experiment ) is calculated. This is the ranking criterion used throughout this work. This ranking then generates a list for atoms to be prioritised for swapping. Once a list of atoms is generated, the possible swap groups are determined and a weighting scheme determines the number of atoms to be swapped. This weighting is biased towards swapping fewer atoms. Swap groups can be customised for any given atom pair or the more general defaults swapping cations, anions and/or vacancies can be specified.