Monte Carlo Calculation of the Thermodynamic Characteristics of Methane and Ethane Adsorption on Graphite.

The thermodynamic characteristics of adsorption (TCAs) of methane and ethane on the basal face of a semi-infinite graphite crystal were calculated by the Monte Carlo method in the Gibbs ensemble. The results obtained using the described calculation algorithm are in good agreement with the literature data. The calculations were performed in the approximation of additivity of atom-atom potentials (AAPs), taken in the Lennard-Jones form (6, 12). When varying the AAP parameters, a quasi-rigid methane molecule was used as a reference. The same AAP parameters make it possible to calculate the adsorption of ethane on graphite under the assumption that the height of the internal rotation barrier does not change during adsorption, but the potential energy of the adsorbed molecule depends on the internal rotation angle. [ABSTRACT FROM AUTHOR]