RELATIVISTIC DENSITY-FUNCTIONAL CALCULATION OF THE TOTAL-ENERGY AND FERMI-SURFACE OF GOLD

For fcc gold we have studied the total energy, equilibrium lattice con stant, bulk modulus and Fermi surface with their dependence on pressur e. The self-consistent calculation in the local-density and warped muf fin-tin approximation applies the modified augmented-plane-wave band-m ethod. The core levels are treated in a fully relativistic way and the valence levels in a quasi-relativistic approximation on the basis of the Foldy-Wouthuysen transformation. Though the Fermi surface properti es and especially the dependence of the extremal orbit areas on pressu re are in good agreement with other calculations and experimental valu es, careful convergence tests offer the quasi-relativistic approximati on as source of large errors in the properties which are derived from the total energy.