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

Results of new simulations for n-butane, n-decane, n-hexadecane, and 2-meth ylbutane at different state points for seven different united atom interact ion 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 t o 80%) and diffusion coefficients are overestimated (up to 250%) as the den sity increases and temperature decreases. Clear evidence was found that the torsion potential is more important at high packing fractions and for long er chains. The comparison of transport coefficients is argued to be a measu re of "goodness" of the interaction potential models resulting in a ranking of the models. (C) 2000 American Institute of Physics. [S0021-9606(00)5121 7-3].