Abstract
A nonequilibrium molecular dynamics method for the calculation of the mutual diffusion coefficient for a mixture of hard spheres is described. The method is applied to a 50-50 mixture of equidiameter particles having a mass ratio of 0.1 for the two species, at a volume of three times close-packing. By extrapolating the results to the limit of vanishing concentration gradient and infinite system size, we obtain a value in statistical agreement with the result obtained using a Green-Kubo molecular dynamics procedure, which is also described. The non-equilibrium calculation yields a mutual diffusion coefficient which decreases slightly with increasing concentration gradient. The Green-Kubo timecorrelation function for mutual diffusion displays a slow decay with time, qualitatively similar to the long-time tail which has been predicted by the hydrodynamic theory of Pomeau.
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Erpenbeck, J.J., Kincaid, J.M. Calculation of the mutual diffusion coefficient by equilibrium and nonequilibrium molecular dynamics. Int J Thermophys 7, 305–317 (1986). https://doi.org/10.1007/BF00500157
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DOI: https://doi.org/10.1007/BF00500157