ANALYTICAL REPRESENTATION OF THE LANG-KOHN DENSITY PROFILES BY THE NUMERICAL FITTING

The numerical fitting of an analytical function representing electron density profile at a jellium surface to the one tabulated by Lang and Kohn is presented. The two sets of parameters entering the electron de nsity profile is proposed. The first one is obtained by purely numeric al fitting, and the second one is calculated under condition that elec tron density profile must satisfy the Budd-Vannimenus theorem. The obt ained parameters are given as analytical functions of the Wigner-Seitz radius r(s) describing mean electron density nBAR in a metal (n-1BAR = 4/3pir(s)3). The comparison of presented electron density profile wi th variational trial function given by Perdew is also discussed.