More detail about the local structure of c-BaSnF 4 , including the behaviour of the Sn lone pair, is provided by analysing structures obtained by quenching from an AIMD simulation. Fig. shows a (001) cross-section through the electron localisation function (ELF) , calculated for a quenched structure from our AIMD simulation. This cross-section intersects with the Wyckoff 4a positions that are occupied by cations in the perfect fluoride structure. Atoms are visible as regions of non-zero ELF density, and each chemical species, Ba, Sn, and F, has a distinct appearance. Ba are visible as bright symmetric rings that are centered approximately on the 4a positions, indicating that barium sits close to its ideal fluorite position. Sn appear as less bright rings, with a bright eccentric lobe that corresponds to the stereoactive lone pair. These lone pairs are generally oriented approximately along ⟨100⟩ directions. The Sn centers appear either to be close to the 4a positions, or, where they are displaced, the displacement appears uncorrelated with the orientation of the lone pair.