Image plane for surface potential

A method of describing the nonlocality of exchange and correlation energy and potential, which gives the correct long-range imagelike behaviour, is adopted in a self-consistentcalculation of a solid surface in the framework of the jellium model. The exchange-correlation potential Vxc(x) whithin the approximation proposed by Gunnarson and Jones, is written for asystem with translational invariance in the plane parallel to the surface. The electron density n(z) and the total effective potential V seen by an electron are self-consistently calculated.We show that within this scheme it is possible to calculate the position of the image plane, as a function of the bulk density.