A pseudo-atom theory for the surface tension of liquid metals

Abstract

The thermodynamics of a liquid-metal surface are investigated using a pseudo-atom model for the ions and electrons. By treating the energy of the electrons as an effective potential for the pseudo-ions, the statistical mechanics of the latter can be evaluated. The surface energy and tension are then derived following the classical Kirkwood-Buff procedure. In the metallic case, the surface energy and tension include indirect effects due to the variation of electron density at the surface as well as the usual direct contribution which arises from the change in the pairwise distribution of atoms caused by the presence of the surface. Some numerical results are presented and compared with experiment. These indicate that, for simple liquid metals, the observed increase in surface tension as a function of increasing bulk electron density is mainly due to an indirect term, that is, the change in self-energy of a pseudo-atom as a function of electron density.