Another approach to probing short-range order in heteroanionic materials is to use computational electronic structure methods, such as Density Functional Theory (DFT) . By calculating the relative energies of structures with varied anion configurations, low-energy anion structures can be identified directly. The high computational cost of electronic structure methods, however, limits their use to relatively small computational cells and to relatively small numbers of possible anion orderings, making it difficult to fully characterise the anion substructure in partially disordered materials. In these cases, it is necessary to use alternative computational methods that accurately describe correlations in anion site occupations at length scales beyond those typical of electronic structure calculations, and ideally allow for rapid evaluation of possible anion arrangements.