Improved results for the potential parameters of methyl and methylene obtained from second virial coefficients of n-alkanes

Abstract

Second virial coefficients of n-alkanes have been evaluated using the rotational isomeric state model. Methyl and methylene groups have been modelled as lennard-Jones (12–6) sites differing in size and in energy well depth. The parameters have been chosen to reprdoce experimental values of second virial coefficients of a number of n-alkanes in a broad range of temperatures. The new proposed parameters improve the description of the experimental data with respect to our previous work (López Rodríguez, A., Vega, C., Freire, J. J., and Lago, S., 1991, Molec. Phys., 73, 691). Moreover, differences in the fitted size and well depth of the methyl and methylene groups appear now as physically reasonable.