DYNAMIC CORRELATIONS IN AN ELECTRON-GAS .1. FIRST-ORDER PERTURBATION-THEORY

Properties of a uniform electron gas in the jellium model are investigated by means of perturbation theory in the electron-electron interaction. First-order diagrams for the proper polarizability are evaluated for arbitrary wave vector and frequency, their singularities and analytical properties are examined, and a reliable numerical procedure for calculating them is established. Quantities such as the dielectric function ε(k,ω), the dynamic-complex-local-field factor G(k,ω), dynamic structure factor S(k,ω), static structure factor S(k), and pair correlation function g(r) are calculated and compared with the corresponding quantities in the random-phase approximation (RPA). The plasmon dispersion in a wide range of momentum transfers and the shape of S(k,ω) versus ω agree well with experimental data for Al, indicating that the first-order theory is reasonable even at rs as large as 2. Significant improvement over RPA is observed. © 1979 The American Physical Society.