Effect of the Dielectric Function on the Phonon Spectrum of Magnesium

Abstract

In this paper we demonstrate that an excellent fit to the phonon spectrum of a simple metal, magnesium, may be obtained with a local pseudopotential containing only two adjustable parameters. We compare the spectrum obtained with a fixed pseudopotential using different dielectric response functions. The Hubbard dielectric function yields phonon frequencies 30% greater than the Kleinman-Langreth one, with the random-phase approximation yielding intermediate frequencies.