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-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.

[1]  William L. Jorgensen,et al.  Optimized intermolecular potential functions for liquid hydrocarbons , 1984 .

[2]  M. Klein,et al.  Calculation of the shear viscosity of decane using a reversible multiple time‐step algorithm , 1995 .

[3]  D. Heyes.  Transport coefficients of the Lennard−Jones fluid by molecular dynamics , 1986 .

[4]  J. Ilja Siepmann,et al.  Transferable Potentials for Phase Equilibria. 1. United-Atom Description of n-Alkanes , 1998 .

[5]  H. Lentz,et al.  Values of p(Vm, T) for n-decane up to 300 MPa and 673 K , 1983 .

[6]  A. Collings,et al.  Torsional crystal technique for the measurement of viscosities of liquids at high pressure , 1971 .

[7]  D. Dysthe,et al.  Fluid transport properties by equilibrium molecular dynamics. I. Methodology at extreme fluid states , 1999 .

[8]  Jean-Paul Ryckaert,et al.  Molecular dynamics of liquid n-butane near its boiling point , 1975 .

[9]  H. C. Andersen.  Rattle: A “velocity” version of the shake algorithm for molecular dynamics calculations , 1983 .

[10]  A. D. Mackie,et al.  Vapour-liquid coexistence curves of the united-atom and anisotropic united-atom force fields for alkane mixtures , 1999 .

[11]  Athanassios Z. Panagiotopoulos,et al.  A New Intermolecular Potential Model for the n-Alkane Homologous Series , 1999 .

[12]  P. Cummings,et al.  Nonequilibrium molecular dynamics calculation of the shear viscosity of liquid water , 1988 .

[13]  Jean-Paul Ryckaert,et al.  Molecular dynamics of liquid alkanes , 1978 .

[14]  Yoshiaki Tanaka,et al.  Viscosity and density of binary mixtures of cyclohexane with n-octane, n-dodecane, and n-hexadecane under high pressures , 1991 .

[15]  S. Toxvaerd.  Equation of state of alkanes II , 1997 .

[16]  Edward J. Maginn,et al.  Molecular Simulation of Poly-α-olefin Synthetic Lubricants: Impact of Molecular Architecture on Performance Properties , 1999 .

[17]  H. D. Cochran,et al.  Molecular dynamics simulations of the rheology of normal decane, hexadecane, and tetracosane , 1996 .

[18]  M. Klein,et al.  Determination of the Pressure−Viscosity Coefficient of Decane by Molecular Simulation , 1996 .

[19]  S. Toxvaerd,et al.  Self‐diffusion in n‐alkane fluid models , 1991 .

[20]  Berend Smit,et al.  Computer simulations of vapor-liquid phase equilibria of n-alkanes , 1995 .

[21]  L. J. V. Poolen,et al.  Measurements of the viscosities of saturated and compressed liquid normal butane and isobutane , 1985 .

[22]  M. Klein,et al.  Decane under shear: A molecular dynamics study using reversible NVT‐SLLOD and NPT‐SLLOD algorithms , 1995 .

[23]  K. Travis,et al.  A direct method of determining the coupling between internal molecular motions and transport properties: Application to liquid n‐butane , 1993 .

[24]  Søren Toxvaerd,et al.  Molecular dynamics calculation of the equation of state of alkanes , 1990 .

[25]  J. Clarke,et al.  The rheological properties of liquids composed of flexible chain molecules: A molecular dynamics computer simulation study , 1987 .