Local-Field Correction and Dynamical Structure Factor of Electron Liquids

The local-field correction (LFC) and the dynamical structure factor S(k , ω) of electron liquids at metallic density are studied by employing the memory function formalism. A density-density response function is expressed in terms of that of a non-interacting electron system and an effective potential. A formally exact expression for the effective potential is shown to have a close interrelationship to the LFC, which is composed of two parts, static and dynamic. The dynamical structure factor S(k , ω) is calculated by taking an interaction part of a second-order memory function to be Gaussian and by introducing parameters for the wavenumber dependence of the low- and high-frequency limits of the effective potential. It is shown by domparing it with the experimental results for Al, Be and Li that the dynamic nature of the LFC plays a fundamental role in determining the properties of S(k , ω) in the intermediate wavenumber domain.