Extended and localized states in the periodic Anderson model

The renormalized quasiparticle states are derived for a periodic Anderson model with a general hybridization matrix element between conduction electrons with two degrees of freedom and f electrons with N degrees of freedom. Only two out of N local f states form the extended quasi-particle bands while N−2 localized states remain. As an illustration we show that the self-energy due to the Kondo effect produces quasiparticle bands and a gap as obtained in the Kondo-boson approach.