Transport Properties of Perfluoroalkanes Using Molecular Dynamics Simulation: Comparison of United- and Explicit-Atom Models

We compare the results of an explicit-atom model (Borodin, O.; Smith, G. D.; Bedrov, D. J. Phys. Chem. B 2002, 106, 9912-9922) for perfluoralkanes with those of a united-atom model (Cui, S. T.; Siepmann, J. I.; Cochran, H. D.; Cummings, P. T. Fluid Phase Equilib. 1998, 146, 51-61) in the prediction of transport properties for short perfluoralkanes. The predicted viscosities from the two force fields are compared against each other and with experiment or correlations of experimental data. We find that the explicit-atom model predicts the Newtonian viscosity of short perfluoroalkane molecules in excellent agreement with experimental data and, in most cases, within experimental error, whereas the united-atom model underpredicts the Newtonian viscosity. Additional dynamical properties, including the diffusion coefficients from both models, are also reported.