Non-local exchange and correlation in the jellium model of surfaces

A method of describing the non-locality of exchange and correlation energy and potential. used by the authors in a density-functional calculation of atomic structure, is now adopted in a self-consistent calculation of a solid surface in the framework of the jellium model. The exchange-correlation potential VXC(z), within the approximation proposed by Gunnarsson and Jones, is written for a system with translational invariance in the plane parallel to the surface. The electron density n(z) and the total effective potential Veff(z) seen by an electron are self-consistently calculated for different electron densities (rs varying from 2 to 6). The behaviour of the different contributions to the surface potential, the intensity of the Friedel oscillations, the surface energies, and the image-plane position z0 are presented, discussed and compared with the results of the local density approximation.