EXPLORATION OF APPROXIMATIONS OF THE KINETIC-EXCHANGE-CORRELATION ENERGY

We present the results of our work to estimate the many-body kinetic-e xchange-correlation energy with a two-body approximation. The approxim ation does not use any adjustable parameters or any functional form. R esults of this approximation used within the corrected effective mediu m method in place of exact numerical integration are provided for Ni, Cu, Rh, Pd, and Ag. Systems that are studied include diatomics, surfac es and the bulk lattice. Among the quantities calculated are surface e nergies, energies of formation for various bimetallic solids, and the barriers and predicted mechanism of the diffusion of Cu on Cu(100). Fi nally, we discuss the validity of approximating a many-body energy wit h a two-body function.