THE MICROCRYSTAL MELTING TRANSITION

Metropolis Monte Carlo simulations of the melting transition of Lennard-Jones microcrystals confined to spherical cavities are reported. While 13 atom microcrystals melt continuously, larger microcrystals containing 201 and 209 atoms exhibit a first-order-like freezing transition to an HCP structure. A simple formula is derived which predicts the marked lowering of the melting temperature for small microcrystals observed in the simulations and which is consistent with experimental results for the melting of metal microcrystals. The Tammann temperature is found to be an accurate indicator of microcrystal melting.