Molecular-dynamics simulation of fluid N2 adsorbed on a graphite surface

A sub-monolayer film of fluid nitrogen adsorbed on a graphite surface has been studied using the molecular-dynamics technique. The molecule–molecule potential consists of a two-centre Lennard-Jones interaction with additional coulombic interactions between partial charges. The surface is modelled as a static external field using a Fourier expansion in the reciprocal lattice vectors of the graphite basal plane.Simulations are performed at a variety of coverages at a temperature close to 75 K. The isosteric enthalpy of the model is in good agreement with experiment. The underlying surface lattice modifies the structure of the adsorbed liquid and there is significant out-of-plane orientational ordering at all the coverages studied.