Self-consistent calculations in the theory of mix-valence

Abstract

Self-consistent perturbation theory is employed for the calculation of physical quantities in mixed valence systems. A single impurity U -> infinity Anderson model is considered with and without crystalline field splitting. The main feature of this method is that excitonic and other correlations are included self-consistently in the theory. In the case of crystalline or magnetic fields coupled non-linear integral equations are obtained for conduction electron scattering amplitudes. These are solved iteratively by retaining the second order terms in the mixing term in the f-electron Green function. Thus temperature dependent level shift and width for the f electron are obtained. Calculated are n sub(f), the f level occupancy, the resistivity and thermopower both &8 functions of temperature, and E sub(f) the f level position relative to the Fermi level.