Effect of substrate potential strength on the melting temperature of a hexane monolayer adsorbed on graphite

In this note we present molecular dynamics (MD) simulation results of the melting transition of a hexane monolayer adsorbed on graphite. The present study was motivated by the recent simulation results of the same system by Hansen et al. [J. Chem. Phys. 98, 4128 (1993)]. Using a United Atom model for the representation of the inter- and intramolecular interactions, and the standard Steele expression for the monolayer-substrate potential, the latter authors obtained a melting temperature for the monolayer-substrate potential, the latter authors obtained a melting temperature for the monolayer which is at odds with experiment by 25%. In contrast, we show that when Steele’s method to model adsorbate–substrate interactions, based on Lorentz–Berthelot’s rule, is used, the transition temperature is in good agreement with experiment. The weaker surface potential also causes a slight increase in the width of the tilt distribution of the molecular axes and a decrease in the number of gauche defects.