Non-Local Electron-Positron Enhancement Factors in Solids

Abstract

Non-local electron—positron correlation effects in solids are studied. The weighted density approximation is applied to calculations of the non-local electron—positron correlation functions. The calculated weighted density approximation electron—positron enhancement factors for the core electrons are compared with those obtained within the local density approximation. Also, differences in the electron—positron enhancement factors due to the s, p, d and f angular momentum channels of the electron charge density are studied. The formalism is applied to ab initio calculations of positron lifetimes in a variety of metals and silicon. The influence of various approximations to the electron—positron interaction on the positron lifetimes is also presented. The weighted density approximation results are compared to those calculated within the local density approximation, the recent generalized gradient approximation and with experimental data.