Determination of the transient polarization response of a dipolar fluid

Recent activity in understanding the dynamics of solvation has also renewed interest in the time dependent behaviour of polar liquids. In this article we report a study of the transient polarization response of a diplar liquid to the instantaneous application of an electric field. The time-dependent response of a Stock-mayer system is examined with nonequilibrium molecular dynamics simulations using two different techniques, the substration method of Ciccotti, Jacucci and McDonald and the transient time correlation function formalism of Evans and Morriss. The two approaches are compared at several field strengths and, unlike earlier work with shear flow in atomic fluids, the former is found to be superior at least for the present implementation. This study greatly expands upon the previous calculations of Petersen, de Leeuw and Perram. However, we are unable to find any data from our simulations that supported their conclusion that nonlinear effects become important at smaller fields than previously thought. The present results are in good agreement with the behaviour predicted by other static field calculations.