A procedure to correlate self-diffusion coefficients in dense fluids by using perturbation theory coupled with the smooth-based-sphere theory was presented and tested against molecular simulations and experimental data. This simple algebraic expression correlated well the self-diffusion coefficients of carbon dioxide, ethane, propane, ethylene, and sulfur hexafluoride. Canonical ensemble molecular dynamics simulations were also performed by using the Hoover-Nose thermostat and the mean-square displacement formula to compute self-diffusion coefficients for the reference intermolecular potential. A good agreement obtained using both methods, when compared with experimental data, suggested that the smooth-effective-sphere theory was a useful procedure to correlate the diffusivity of pure substances.

Dense Fluid Self-Diffusion Coefficient Calculations using Perturbation Theory and Molecular Dynamics. Coelho, L.A.F., Oliveira, J.V., Tavares, F.W.: Brazilian Journal of Chemical Engineering, 1999, 16[3], 319-28