A microscopic model is proposed for the fast ion transport in solids.
It is suggested that the change of bonding which occurs locally and fl
uctuates in time is the key mechanism responsible for the superionicit
y. The change of bonding is considered to be driven by the lattice vib
ration. In order to corroborate the idea, the bonding nature of binary
compounds have been studied by using a pseudopotential theory. It is
concluded that the real space pseudopotential which reflects the valen
ce electron distribution, provides useful information to understand th
e link between the ion transport and the electronic structure of the m
aterials.