To quantify the degree of spatial correlation between the Sn lone pairs and nearby fluoride ions, we have calculated the lone-pair-fluoride-ion polar spatial distribution function g(r, θ) (Fig. ). This distribution function describes the time-average fluoride-ion coordination environment around tin, as a function of distance from the central tin cation, r, and the angle between the Sn-F vector and the lone-pair-orientation vector, θ. On the reverse side of the central tin from the lone-pair, there is a clear feature at r = 2.1 Å with maximum intensity at 135 • , i.e., the position of the tetrahedral 8c site if the lone pair is oriented towards the center of the opposite cube-face. On the lone-pair side, however, there is a distinct lack of structure, and fluoride density is instead smeared out in a broad region from r > 3 Å. This distribution function is consistent with the model proposed from inspection of the time-average fluoride-ion density plot (Fig. ): the Sn lone pair is preferentially oriented towards one face of the enclosing cubic site, and fluoride ions that would occupy the corners of this face in a perfect fluorite structure are repelled by the lone pair, which strongly disrupts the fluoride structure in the vicinity of the lone pair.