Fluid transport properties by equilibrium molecular dynamics. III. Evaluation of united atom interaction potential models for pure alkanes

Abstract

Results of new simulations for n-butane, n-decane, n-hexadecane, and 2-methylbutane at different state points for seven different united atom interaction potential models are presented. The different models are evaluated with respect to the criteria simplicity, transferability, property independence, and state independence. Viscosities are increasingly underestimated (up to 80%) and diffusion coefficients are overestimated (up to 250%) as the density increases and temperature decreases. Clear evidence was found that the torsion potential is more important at high packing fractions and for longer chains. The comparison of transport coefficients is argued to be a measure of “goodness” of the interaction potential models resulting in a ranking of the models.