Evidence against a crystal instability in melting

Abstract

Since Bern's original suggestion¹, melting has frequently been attributed to a crystal instability although its one-phase approach has been objected to. Using a molecular dynamics computation of the behaviour of a 336-atom Lennard–Jones system, and exploiting the inherent limitations on model size and simulation time, we have found a crystal–liquid instability. It falls outside the density interval for thermodynamic melting, however, and we conclude that it is not true melting. We have also discovered an isothermal liquid–glass transition on compressing the liquid, and this occurs at a density within the transition interval. The results reported here are consistent with the first-order nature of melting and provide new insight into the difference between the crystalline and liquid states.