Theory of Surface Melting and Non-Melting

Abstract

The idea that crystal melting might be a surface-initiated process when the liquid wets its own solid is very old [1,2]. A massive amount of macroscopic and semimacroscopic evidence for the appearance, just below the triple point temperature T _M of a quasi-liquid film at the solid-gas interface, particularly of molecular crystals, has been collected by the chemical physicists [3]. More recently, with the advent of powerful surface physics tools, the study of this problem has begun at the microscopic level. Several crystal surfaces which melt -i.e., where a growing quasi-liquid layer forms very near but below T _M - have been identified [4]-[7]. Other surfaces have also been found, which exhibit what might be called “non-melting”, Le. no quasi-liquid layer appears at all [8], or if it appears, it does not grow as TM is approached [9].