Confluence of extended and localized states: Implications on the Mott-Cohen-Fritzsche-Ovshinsky model

Abstract

The possibility and consequences of the presence of the poles of the Greens function (in the Anderson model) in the Riemann sheets of a cut Z plane have been discussed. Such poles lack the pure-point nature and correspond to states formed by a confluence of degenerate extended and localized states. The character of these states is different from the pure extended and localized states both in the mathematical and in the physical sense. They form a new regime of slow diffusion in the energy spectrum, which indicates that there should exist another critical energy, like the mobility edge, that separates the new regime of the spectrum from the absolutely continuous part. © 1990 The American Physical Society.