Discussing ion jumps in the context of phonon fluctuations is a novel concept and may be a first step towards a lattice dynamical theory of ion transport. Generally, one could use the jumpdirection projected density of states for each Ag + site to elucidate jump probabilities for each frequency and each (compare Figure ). From our frequency-dependent analysis, we reach an important conclusion that lower frequencies are more beneficial for ionic transport (Supplemental Note 6), independent of the material, temperature or activation barrier. This is a crucial insight for ion conduction research showing that the local jump dynamics need to be tailored rather than the global lattice dynamics. The inherently low frequencies of Ag + vibrations in the Ag8MSe6 argyrodites may thus be a contributing factor to their superionic behavior.