Self-consistent screening of impurity atoms in nearly-free-electron metals

Abstract

A method of calculating the potential due to a substitutional impurity in a nearly-free-electron metal is presented. The solvent is approximated by a free-electron gas and the impurity potential incorporates the potential due to the core of the impurity, the potential due to the uniform electronic density, the screening potential and a correction for exchange. The impurity potential is calculated self-consistently using a method similar to that used by Islam and Ball (1970) to calculate the potential of a pseudoatom in a pure metal. With their original method, the calculated potentials have a long range and the results are not in agreement with experiment. To make the potentials more physically realistic, they are reduced outside the impurity cell by an exponential cut-off factor. Phase-shifts for LiMg, LiAg, LiCd, LiIn, NaCd, NaIn are presented and the spin-flip scattering cross-sections [sgrave] are calculated. The results are in good agreement with experiment, especially when the dilatation of the lattice is approximately taken into account.