Melting behavior of quasi-two-dimensionalN2adlayers deposited on graphite

The melting behavior of partial and complete ${\mathrm{N}}_2$ monolayers on graphite is examined using a Monte Carlo procedure in conjunction with the multiple histogram method. It is found that vacancies inherent in partial monolayers, and those thermally induced by out-of-plane motion at or near monolayer completion, are important factors in predicting the density dependence of the melting temperature. Calculated at various surface densities are the melting temperatures, specific heats, order parameters, probability distributions for molecular positions and orientations, and fluctuations in these quantities. With this information the mechanism of the melting transition is elucidated, and the temperature and density dependence of the specific heats and order parameters is explained. © 1996 The American Physical Society.