Self-consistent perturbation theory for dynamics of valence fluctuations - III. Zero-temperature limit

Dynamical properties of valence-fluctuating systems are studied at absolute zero of temperature. The self-consistent perturbation theory developed for rare-earth impurity systems is used with some refinement. The theory takes account of the orthogonality catastrophe caused by hybridization of 4 f and conduction electrons. Extensive numerical results are reported for the 4 f-electron density of states ρ{variant}_{4 f}(e{open}) and the dynamical magnetic susceptibility χ(ω). The results cover both the intermediate-valence and nearly integral-valence regimes of a model Ce impurity system. The present theory gives reasonable overall feature of dynamics including a sharp peak in ρ{variant}_{4 f}(e{open}∼0) in the Kondo regime. However, the low-frequency limit of dynamical quantities is not consistent with the Fermi-liquid property. It is shown that interpolation of the present results and those by the Fermi-liquid theory is possible. Hence accurate dynamical information is obtained over a wide excitation-frequency range.