A molecular dynamics (MD) study of methane in silicalite-1: A novel Møller-Plesset potential energy surface

Abstract

A novel methane/silicalite-1 potential function for MD simulations has been developed using quantum chemical calculations at a Møller-Plesset secondary level/ 6–31 G * basis set. As an application a diffusion coefficient of 5.55×10 −9 m 2 .s −1 and heat of adsorption of −5 kcal.mol −1 have been obtained for a concentration of one methane molecule per intersection and reasonably match with available studies. In contrary, methanemethane radial distribution functions reveal a first peak at 6.3at the low loading (one molecule per intersection) and of 5.4at the highest loading (four molecules per intersection) instead of the first peak at about 4at all concentrations [14], and interpreted there as a consequence of methane-methane Lennard-Jones parameters use. It is, then, demonstrated that the appearance of the peak at 4.0is caused primarily by an unbalance of the methane/methane and silicalite-1/methane pair potentials. With consistence, the present analysis exhibits favorable resident sites at various concentrations in the zigzag channel.