ABSTRACT
This chapter describes the formal properties of dielectric response functions. It shows how such functions both provide a compact characterization of, and offer considerable physical insight into, a number of phenomena of interest in electron systems. The chapter considers an elementary discussion of the effective electron interaction in simple metals. It also considers the consequences of the coupling between quantum plasma in its ground state and an external longitudinal phonon field. The chapter also describes the coupling between the electron liquid and a transverse electromagnetic field. It includes the microscopic generalization of the semi classical approach, in which the electron response is specified in terms of a conductivity or dielectric tensor. The chapter addresses the polarization processes, in which phonons as well as electrons are involved. It also includes an explicit quantum-mechanical treatment of the coupled electron-photon system and Raman scattering of light.
