Mutual diffusion in a liquid mixture of argon and krypton

Molecular dynamics simulations are performed for an equimolar mixture of argon and krypton. The concentration-fluctuation autocorrelation functions Fm, the collective and individual velocity autocorrelation functions Zm and Zs, and the mean-square displacements are measured. The mutual diffusion coefficient determined from Fm is less than measured previously, but this is due to the approximation Q = 1 in the previous measurements for the thermodynamic factor Q which we find less than unity. We also note that Zs exhibits an interesting temperature-dependent late-time behavior which arises from the back scattering effect.