APPROXIMATE NONLOCAL-EXCHANGE-CORRELATION POTENTIAL AS THE IMAGE POTENTIAL FOR METALS

A method is presented for applying the concept of an exchange-correlat ion electric field due to the exchange-correlation hole when determini ng the approximated nonlocal-exchange-correlation (NLXC) potential in the surface region of a metal. Our approximation for the electron-hole separation based on the theory is proposed by Serena, Soler, and Garc ia. The NLXC potential obtained shows the correct classical imagelike limit outside the metal without any extra boundary conditions. The met hod presented is also applied to determining the NLXC potential of a o ne-dimensional metal-vacuum-metal (MVM) interface barrier. This method gives the physical background of the approach for a MVM barrier sugge sted by Garcia and incorporates the classical multi-image potential in the NLXC potential of a MVM junction.