Transient-time-correlation functions and the rheology of fluids.

Abstract

In this paper we use the recently developed transient-time-correlation function formalism (TTCF) to study the transient rheology of classical fluids. We compare this approach to the calculation of fluid transport properties using the Green-Kubo method (valid only in the linear-response regime), with direct nonequilibrium molecular dynamics (NEMD) simulations, and with the NEMD subtraction technique. The various approaches are compared for a system undergoing isothermal, planar Couette flow. Although less efficient than direct NEMD at large strain rates, the TTCF results agree with direct NEMD to high accuracy. At low strain rates where direct NEMD is not applicable, the TTCF approach is clearly more efficient than the subtraction method.