Ensemble dependence of the transient fluctuation theorem

The fluctuation theorem gives an analytical expression for the probability of observing second law violating dynamical fluctuations in nonequilibrium systems. At equilibrium, statistical mechanical fluctuations are known to b e ensemble dependent. In this paper we generalize the transient and steady- state fluctuation theorems to various nonequilibrium dynamical ensembles. T he transient and steady-state fluctuation theorem for an isokinetic ensembl e of isokinetic trajectories is tested using nonequilibrium molecular dynam ics simulations of shear flow. (C) 2000 American Institute of Physics. [S00 21-9606(00)50433-4].