Molecular dynamics simulation of noble gas adsorption on graphite: New effective potentials including many-body interactions

Abstract

We have investigated noble gas adsorption on graphite surface at constant temperatures using well known two-body potentials. We have also considered quantum effects for Ne-Ne interactions using the FH approximation. We have also distinguished multilayer adsorption at higher pressures (argon and xenon, for example). In order to consider the many-body interactions (UMB), a simple and accurate many-body expression has been used with the two-body potentials (U2B) as: UMB=βU2B. The parameter β corrects the difference between the two-body results and the experimental data which not only account for the three-body interactions but also for other effects (such as the three-body repulsions or quantum effects). The effect of this many-body potential for the adsorption system is to decrease the well depth of the potential which makes the potential less attractive. The many-body interaction also decreases the two-body adsorption energy. It is also shown that these effects are greater at higher pressures where the many-body interactions dominate. A modified Wang and Sadus equation (MWS) for consideration of the many-body effects for argon adsorption on graphite has been also proposed. We have also investigated the effect of the many-body interactions on two-body radial distribution functions and self-diffusion coefficients of the different adsorbed molecules.