Melting transition of near-monolayer xenon films on graphite: A computer simulation study. II.

Abstract

Xenon films of greater than one monolayer thickness are simulated using the molecular-dynamics technique. If the total substrate area and coverage are held constant, we find that the first layer of the xenon film melts in an apparent continuous manner over a small temperature interval and is consistent with two-phase, solid-liquid coexistence. The quantitative features of the correlation functions are in excellent agreement with recent x-ray experiments [P. A. Heiney et al., Phys. Rev. Lett. 48, 104 (1982) T. F. Rosenbaum et al., Phys. Rev. Lett. 50, 1791 (1983)]. If the spreading pressure and total coverage are held constant, we find that the melting transition is first order. This is in conflict with the conclusions of Heiney et al. based on constant-chemical-potential experiments but is consistent with the constant-area and -coverage simulation. A possible explanation is proposed.