The previous subsection has already shown that there is no one-to-one correspondence between the energetic ordering of fluoride sites obtained from the DFT optimizations and the occurrence of dynamic disorder in the AIMD simulations: There are some cases where the observations can be understood on the basis of the optimization results, because the primary (initial) fluoride location and the secondary site at which fluoride resides after the dynamic event are close in energy, i.e., the value of ΔErel obtained for the secondary fluoride position is small. However, this is not always the case, as highlighted for IFR and CHA. More insights can be gleaned by looking at the F•••Si distances, i.e., distances from fluoride anions to surrounding Si atoms to which they are not bonded. These values are tabulated in Table , considering all distances below 3.5 Å (F-Si bond lengths are also included for completeness). The longest distances to second-nearest neighboring Si atoms are found in NON and STF, F@Si10, where all F•••Si distances exceed 2.8 Å, whereas the corresponding distances in the other zeolites fall between 2.59 and 2.72 Å. This apparent lack of relatively close Si atoms can explain why no dynamic disorder occurs in NON and STF, F@Si10 at 298 K. The qualitative difference between the two systems at higher temperatures can also be understood on the basis of the different distances to the second-nearest neighbors (NON: 2.90 Å; STF, F@Si10: 2.81 Å).