DETERMINATION OF THE POTENTIAL PARAMETERS OF A SITE MODEL FROM CALCULATIONS OF 2ND VIRIAL-COEFFICIENTS OF LINEAR AND BRANCHED ALKANES

A previously established method to assign Lennard-Jones parameters for the methyl and methylene site groups in n-alkanes is now generalized to the case of branched alkanes. The method is based on Monte Carlo ca lculations of the binary cluster integral of the chain molecules, and their comparison with experimental data of second Virial coefficients in the gas phase. We have arrived at a single set of values for the pa rameters epsilon and sigma of the different sites, CH3, CH2, CH and C, that reproduces adequately the virial coefficient data of linear and branched molecules, and also of their mixtures. This way we have also clarified the validity of the different alternative sets proposed in o ur earlier study for n-alkanes.