FERMI-SURFACE OF NOBLE-METALS - FULL-POTENTIAL GENERALIZED-GRADIENT-APPROXIMATION CALCULATIONS

The Fermi surface (FS) of the noble metals has been studied theoretica lly in order to compare calculations based on a full-potential techniq ue to calculations based on atomic-sphere approximation (ASA). Also, t he effect of replacing the local-density approximation (LDA) with the generalized gradient approximation (GGA) for the exchange-correlation potential has been studied here. In the present work we have used the generalized gradient approximation derived by Perdew and Wang (PW91). We find that replacing the ASA with a full potential causes a larger m odification of the calculated FS, compared to replacing the LDA with t he GGA. Our calculations demonstrate that full-potential calculations combined with the LDA improve the FS of Cu and Ag relative to the resu lts of the atomic-sphere approximation. If the full-potential method i s combined with PW91 one obtains further improvements for these two me tals. For Au, the full-potential calculations, based on LDA or GGA, do not give any improvement over results obtained from the atomic-sphere approximation.