Intermediate valence. Phase diagram and kondo behaviour in a simple model.

Abstract

We have studied an infinitely narrow band versión of the Anderson Hamiltonian. Including a Coulomb repulsion between localized and band states in the mean field approximation, we have been able to describe metal-insulator phase transitions and different properties characteristic of interm edíate valence in both phases. These include: non-integer occupation, specific heat, saturating static magnetic succeptibility and dynamical properties such as Mössbauer spectra and spin flip neutron spectra. We discuss for what range of valúes of the parameters some results can be reproduced by a narrow band versión of the Kondo Hamiltonian.