Application of transient correlation functions to shear flow far from equilibrium

Abstract

Morriss and Evans recently developed a generalization of the Green-Kubo relations which is valid for nonequilibrium steady states far from equilibrium. This formalism relates the nonequilibrium response to transient time correlation functions which connect the nonequilibrium steady state to the equilibrium state. In the linear regime, the transient time correlation functions reduce to simple equilibrium Green-Kubo relations. The transient time correlation function method thus provides a long-sought-after fundamental relation between nonequilibrium molecular dynamics algorithms and the Green-Kubo formalism which is only valid close to equilibrium. In this paper we demonstrate the use of the transient time correlation function formalism for isothermal planar Couette flow. The results show that the nonlinear steady-state response can be calculated by integrating the appropriate transient response time correlation function. In particular, the nonlinear shear stress and pressure calculated in this way agree with the values calculated directly.