Dynamical susceptibility of intermediate valence systems

The transverse susceptibility if magnetic systems described by the Anderson model is calculated evaluating the self energy for the two particle Green function. The results are applied to semiconductors and metals. In the first case a shift in the resonance frequency is obtained as well as a continuum of excitations corresponding to the promotion of electrons from the localized state to the conduction band states. In the metallic case a Korringa relation for the relaxation time in the magnetic limit is obtained. The real and imaginary parts of the self energy are given as functions of the distance from the localized level to the Fermi level.