Construction of a potential energy surface for molecular dynamics studies of methane adsorbed in zeolites

A potential for the interaction of methane molecules with the framework ato ms of siliceous zeolites is developed empirically. The CH4 molecule is cons idered in the spherical approximation. The interaction potential includes r epulsion, dispersion, and induction energy. It is shown that even if the ef fective charges on the framework oxygen and silicon atoms are large, the co ntribution of the induction energy is weak in comparison with those of disp ersion and repulsion energies due to compensation effects. The calculated p arameters of a Lennard-Jones potential are compared with those used in prev ious MD calculations. As an application we calculate diffusion coefficients and the heat of adsorption of methane in silicalite which can be compared to available experimental data.