SURFACE-INDUCED MELTING AND FREEZING .2. A SEMIEMPIRICAL LANDAU-TYPE MODEL

Thermodynamic criteria are derived for the occurrence of surface-induced melting and freezing in a semi-infinite system. Use is made of a mean-field theory of the Landau-type. The parameters which enter the Landau free energy functional are expressed in terms of known interfacial free energies. Expressions are obtained for the order parameter profile in the surface region and for the temperature-dependent thickness of the molten (frozen) surface layer. The results explain recent observations of surface melting (or nonmelting) at differently oriented crystal faces of Pb and account for the general absence of surface-induced freezing effects in liquids.