OPTICAL PROPERTIES OF THE FREE ELECTRON GAS

Abstract

The aim of the present work is to calculate the wave vector q and the optical frequency ro dependence of the dielectric function E(q,ro) in the energy range 0.0 Ry - 2.0 Ry , for the simple metals Na , K and Al in the random phase approximation (RPA) and beyond the (RPA) taking into consideration; (a): the electron - electron collisions by using relaxation time approximation where the conservation law of electrons number is satisfied , (b): the local field effect by inserting the short range exchange and the correlation effect and (c): the effect of ion core polarizability on the free electron dielectric function , the resulting dielectric function is then called the modified dielectric function .