SIMULATION OF SURFACE EXCESS CONCENTRATIONS FOR A BINARY HYDROCARBON MIXTURE ON GRAPHITE

We perform Molecular Dynamics simulations of thin hydrocarbon films ad sorbed on the basal plane of graphite to determine structural and ther modynamic properties. Specifically we study the behaviour of liquid be nzene/n-heptane mixtures. The intra adsorbate and the adsorbate-substr ate interactions are described using a phenomenological force field wh ose careful parameterization will be reported in a following paper. Th e foremost quantity we calculate is the adsorption isotherm, i.e. the surface excess concentration as a function of the benzene bulk mole fr action at T = 283 K, which is in quite reasonable agreement with the e xperiment. Along with the isotherm we compare the surface induced orde ring of the two components in terms of order parameter profiles.