Generalized Langevin equation for nonequilibrium systems

We derive a generalized Langevin Equation (GLE) for the evolution of an arb itrary phase variable in a classical fluid that is initially at equilibrium and is subsequently subjected to an external field and a thermostat of the type used in nonequilibrium molecular dynamics computer simulations. The n onequilibrium steady state GLE is shown to have the same form as the equili brium GLE at long times. We use our generalized Langevin equation to derive a simple Langevin equation for the motion of a single heavy Brownian parti cle in a solvent under steady state planar shear. (C) 2001 Elsevier Science BN. All rights reserved.