Time correlation functions in a binary liquid mixture

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Abstract
The time correlation functions involving heat and particle fluxes in a binary argon-krypton mixture with Lennard-Jones interactions are found using both isoenergetic and isokinetic equilibrium molecular dynamics simulations. The heat-current–diffusion-current cross function does not appear to have been evaluated before. The Green-Kubo integral of this function has nearly canceling positive and negative parts and so is not a good way of obtaining the Soret or Dufour coefficient. Integration of the diffusion-current autocorrelation function yields a value for the mutual diffusion coefficient in agreement with an earlier nonequilibrium simulation but at variance with previous isoenergetic (or Newtonian) equilibrium simulation results. It is conjectured on the basis of these results that isokinetic simulations may have smaller system-size dependence than isoenergetic ones.