Electron-ion correlation potentials in the density-functional theory of H and He plasmas.

Abstract

In previous applications of the density-functional theory to plasmas, particle correlation effects were included via the exchange-correlation potential ${W}_{\mathrm{xc}{}^{e\mathrm{\ensuremath{-}}e}}$ for the electrons, and the ion-correlation potential ${W}^{i\mathrm{\ensuremath{-}}i}$ for the ions, while the electron-ion correlation potentials ${W}^{e\mathrm{\ensuremath{-}}i}$ were neglected. These electron-ion correlations appear beyond the random-phase approximation and are expected to be small for liquid metals, but are non-negligible in plasmas of light elements. In this work, we consider an approximation for electron-ion correlations that exploits the properties of the direct correlation function and the local-field correction familiar in the theory of liquids. Calculations that include the effects of temperature on the electron density and on the correlation potentials have been performed for hydrogen (H) and helium (He) plasmas with the plasma-coupling parameter \ensuremath{\Gamma} ranging from 0.07 to 5. The effects of electron-ion correlations on the structure factor, ionization, and the interaction energy are discussed.