Fermi-Surfae Sum Rule and its Consequences for Periodic Kondo and Mixed-Valence Systems

Abstract

The Friedel sum rule for impurities is related to the Luttinger requirement that the volume of the Fermi surface of a crystal is independent of interactions. As a consequence important results derived by use of the Friedel sum rule, e.g., the $T\to 0$ properties of the Kondo problem, can be extended to periodic cases. Considered explicitly are the remarkable consequences for Fermi surfaces and Fermi-liquid properties of periodic Kondo and mixed-valence systems.