Electron Correlations and Dielectric Function of Electron Gas at Metallic Densities

Abstract

Short-range correlations in an electron gas are investigated from a diagrammatic analysis of perturbation theory. An infinite sum of electron-electron ladder diagrams is shown to be indispensable for the short-range correlation at metallic densities. A new approximate expression for the dielectric function e ( q ,ω) is presented, which is an interpolation between the random phase approximation (RPA) for small q and an infinite sum of ladder diagrams between electrons with antiparallel spins for large q .