Enhancement of Electron Density around Positive Point Charges in Metals and Lifetimes of Positrons

Abstract

By means of approximate self-consistent field calculations using a model of a finite metal with \ensuremath{\sim}2000 electrons, it is shown that over the range of densities appropriate to metals under normal conditions, the density at the position of a single positive charge varies by a factor of about 2, whereas the variation in the mean electron density ($\frac{3}{4\ensuremath{\pi}{{r}_{s}}^{3}}$) is an order of magnitude greater. In a simple Hartree calculation of the type reported here, a bound state occurs when ${r}_{s}>4$ atomic units. Some brief remarks are made on the application of these results to the calculation of the lifetimes of positrons in various metals.