Dielectric response of quantum plasmas in thermal equilibrium

The dielectric function $\epsilon (k,\omega )$ of an electron plasma in thermal equilibrium is calculated for all degrees of plasma degeneracy. Previous results for degenerate and nondegenerate plasmas, based on quantum-mechanical, classical, or semiclassical approaches, are contained in this analysis. Expressions for the real and imaginary parts of $\epsilon (k,\omega )$ are given for the cases of low and high frequencies and long and short wavelengths. In particular, the roles of thermal and quantum effects on screening, collective plasma resonance, and single-particle behavior are discussed.