Perturbation theory for nonperiodic Anderson model

The periodic Anderson model consisting of electrons of conductivity and $f$-localized electrons is studied. One-knot hybridization of these two subsystems of electrons is treated as a perturbation. A new diagrammic method based on multiparticle one-knot irreducible Green's functions for $f$-electrons and on the usual Wick theorem for the subsystems of electrons of conductivity is developed. The Dyson equations for one-particle Green's functions and relations between them are found. The results are exact and can be used for selfconsistent аpproximations. In the Habbard I approximation the spectrum of one-particle exitations is studied.