alkanes, molecular dynamics, Lennard-Jones potentials


Mutual diffusion coefficients for selected alkanes in carbon tetrachloride were calculated using molecular dynamics and Lennard-Jones (LJ) potentials. Use of effective spherical LJ parameters is desirable when possible for two reasons: (i) computer time is saved due to the simplicity of the model and (ii) the number of parameters in the model is kept to a minimum. Results of this study indicate that mutual diffusivity is particularly sensitive to the molecular size cross parameter, σ12, and that the commonly used Lorentz–Berthelot rules are inadequate for mixtures in which the component structures differ significantly. Good agreement between simulated and experimental mutual diffusivities is obtained with a combining rule for σ12 which better represents these asymmetric mixtures using pure component LJ parameters obtained from self-diffusion coefficient data. The effect of alkane chain length on the mutual diffusion coefficient is correctly predicted. While the effects of alkane branching upon the diffusion coefficient are comparable in size to the uncertainty of these calculations, the qualitative trend due to branching is also correctly predicted by the MD results.

Original Publication Citation

Stoker, J. M. and R. L. Rowley. "Molecular dynamics simulation of real-fluid mutual diffusion coefficients with the Lennard-Jones potential model." The Journal of Chemical Physics 91 (1989): 367-3676

Document Type

Peer-Reviewed Article

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Ira A. Fulton College of Engineering and Technology


Chemical Engineering