Nonequilibrium velocity distributions in liquids: systems under shear.

A Green-Kubo expression for the nonequilibrium correction to the velocity distribution function is studied in a molecular dynamics simulation for systems interacting through a 6-12 potential and undergoing linear shear. As a function of velocity, the first correction to the distribution function has a form similar to what would be obtained from the Boltzmann-Enskog equation, although the amplitude is qualitatively different, except at infinite dilution. The difference comes from elastic effects seen in the short-time behavior of the underlying time correlation functions.