Band-like states for ionic conduction

Facile, ultrafast migration of ions is observed in several systems. Our concern in this paper is primarily with cation transport across phospholipid membranes via cylindrical channels. By means of an analogy with the Mott-Hubbard metal/non-metal transition, we show that band-like ionic conduction through cylindrical channels is possible. In particular, if the height of the intrinsic barrier between potential-energy minima is approximately the same as the width of the 'conduction band' which can be defined for the system, then band-like transfer is possible. The existence of band-like states does not guarantee high conductivity. However, the underlying band-like structure may interact non-linearly with the phonons to yield solitary waves and even solition states. Such solitary waves migrate with minimal degradation and thus ensure high conductivity.