First-order model for the surface properties of liquid metals: Electroneutrality conditions and interionic correlations
Abstract
A previously presented model for simple liquid metals, in which the electron–ion pseudopotential is treated in first order, is used to calculate some surface properties. The electron density profile is obtained by minimization of the surface energy of a reference sysytem and the ionic profile is taken as a step function. In the surface, we write the ion–ion distribution function in a form which reduces to the bulk radial distribution function in the interior, while satisfying the local electroneutrality condition as well as other necessary constraints. The bulk distribution function is that for neutral hard spheres. Calculated energies are of the right size for most of the metals considered, in spite of the fact that the components are sometimes an order of magnitude larger than the surface energy itself. The sensitivity of the surface energy to the approximations in the model are discussed. The classical Fowler contribution of the Coulombic interaction of the ions is found to be markedly reduced by the modification demanded by the electroneutrality condition. Some directions for future improvements are indicated.