In addition to the zeolites listed above, all-silica chabazite (CHA) was included as a system for which the experimental findings do not allow for definitive conclusions regarding the dynamic disorder. The crystal structure of as-synthesized Si-CHA has been reported by Villaescusa et al. Despite extensive disorder of the fluoride anions, which are distributed over twelve symmetryequivalent positions in the double six-ring cages (Figure ), and evidence for F-Si bonds in the In order to arrive at a tractable number of zeolite models with different fluoride locations, the following considerations were made: First, only positions inside those cages where fluoride is found in the experimental structures were considered (in other words, positions inside the cages shown in Figure ). This reasoning follows the findings of Pulido et al., who found that the interaction with the OSDA determines in which cages the fluoride anions reside. Second, vertices of a given cage were only taken into account if (at least) three of the cage edges meet at that vertex, because the formation of an [SiO4F] -trigonal bipyramid can only be expected when the Si-F connection line points towards a face of the SiO4 tetrahedron. Vertices where only two edges meet were not considered, because a fluoride anion that points toward the cage centre would lie on the edge of the SiO4 tetrahedron, leading to short O-F contacts and strong repulsion. Further details of the model preparation are given in the Supporting Information (page S2).