Long range corrections for computer simulations of adsorption

Long range corrections are routinely applied to simulations of bulk fluids by assuming that the radial distribution function is unity beyond a certain cutoff radius for pairwise interactions. Similar long range corrections for gas-solid interactions in adsorption frequently are ignored because of the anisotropic structure of the solid. However, the error associated with assuming isotropy beyond the cutoff radius is small compared with the magnitude of the long range correction. The long range correction to the Henry constant for a cutoff radius of 13 Å is 14% for CH₄ and 70% for SF₆ for adsorption in silicalite at 298 K. The large errors incurred by neglecting long range corrections can be concealed by increasing the well depth of the gas-solid interaction, but this approximation reduces the accuracy and portability of the potential parameters. Consistency in the cutoff radius is more important than the inclusion or neglect of long range corrections to the energy.