To model the equilibrium structure and dynamics of c-BaSnF 4 , we performed ab initio molecular dynamics (AIMD) using the Vienna ab initio simulation package (VASP) . We used the revised Perdew-Burke-Ernzerhof generalized gradient approximation PBEsol exchangecorrelation function . Interactions between core and valence electrons were described within the projectoraugmented-wave (PAW) method , with cores of [Kr] 4d 10 for Ba, [Kr] for Sn, and for F. We simulated a 6 × 6 × 6 supercell, starting from a cation-disordered fluorite structure with a special-quasi-random configuration of Ba and Sn over the Wyckoff 4a cation sites, that we generated using the icet package . This 6 × 6 × 6 special-quasi-random structure best approximates the Ba/Sn correlations for an infinite lattice with a fully-random arrangement of cations .