Non-linear Self-consistent Screening Applied to Simple Metals

Abstract

<p>Non-linear, approximately self-consistent calculations of the electron density distribution around a proton and a helium nucleus in otherwise uniform electron gases of different densities have been performed, and applied to two types of problems.</p> <p>One of these is the energies and equilibrium positions of isolated He in Al and Mg, and of pairs of both H and He in these metals. For the pair potential between the impurities an expression based on the density functional formalism has been used. Both perfect hosts and ones with single vacancies are considered. It is found that when occurring singly, each of these impurities is attracted at least to the vicinity of a vacancy in either metal, and that when two impurities are near a vacancy, the minimum energy configuration occurs with them bracketing the defect, relaxed towards it from the interstitial sites.</p> <p>The superconductivity of metallic H has been considered, using non-linear calculations to determine the electron-proton and proton-proton potentials. It is found that this causes an enhancement of the transition temperature Tc over that obtained using linear response theory. Tc also depends strongly on the structure assumed, being computed as up to 280°K for the face-centered cubic structure, and less than 10°K for body-centered cubic.</p>