Title: COMPUTER SIMULATIONS OF THE DYNAMIC PROPERTIES OF METHANE IN A MODEL SILICA GEL
Authors: T.Patsahan (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine; E-mail: tarpa@icmp.lviv.ua), A.Trokhymchuk (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine), M.Holovko (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine; Ivan Franko Lviv National University, 12 Dragomanov Str., 79005 Lviv, Ukraine)

Molecular dynamics (MD) simulations are reported for a Lennard-Jones fluid adsorbed into a model silica gel to study the dynamic properties of the adsorbed methane molecules. The mean-square displacement and velocity autocorrelation function of the adsorbed molecules are calculated for a set of supercritical temperatures at low (gas-like) and high (liquid-like) fluid densities and compared with the same data for a bulk fluid. The evaluated radial distribution functions illustrate the formation of a contact layer on the pore surface that is consistent with the decrease in the mobility of the adsorbed molecules in a porous environment. The calculated self-diffusion coefficient indicates a good quantitative agreement with the measured data for methane confined to the silica gel.

Key words: fluid, porous medium, diffusion, simulation, molecular dynamics
PACS: 02.70.Ns, 45.20.Dd, 51.20.+d, 61.43.Gt