Time dependent current in a nonstationary environment: a microscopic approach

Abstract

Based on a microscopic system reservoir model, where the associated bath is not in thermal equilibrium, we simulate the nonstationary Langevin dynamics and obtain the generalized nonstationary fluctuation dissipation relation (FDR) which asymptotically reduces to the traditional form. Our Langevin dynamics incorporates non-Markovian process also, the origin of which lies in the decaying term of the nonstationary FDR. We then follow the stochastic dynamics of the Langevin particle based on the Fokker-Planck-Smoluchowski description in ratchet potential to obtain the steady and time dependent current in an analytic form. We also examine the influence of initial excitation and subsequent relaxation of bath modes on the transport of the Langevin particle to show that the nonequilibrium nature of the bath leads to both strong nonexponential dynamics as well as nonstationary current. (c) 2008 American Institute of Physics.