We study the driven Brownian motion of hard rods in a one-dimensional cosine potential with an amplitude large compared to the thermal energy. In a closed system, we find surprising features of the steady-state current in dependence of the particle density. The form of the current-density relation changes greatly with the particle size and can exhibit both a local maximum and minimum. The changes are caused by an interplay of a barrier reduction, blocking and exchange symmetry effect. The latter leads to a current equal to that of non-interacting particles for a particle size commensurate with the period length of the cosine potential. For an open system coupled to particle reservoirs, we predict five different phases of non-equilibrium steady states to occur. Our results show that the particle size can be of crucial importance for non-equilibrium phase transitions in driven systems. Possible experiments for demonstrating our findings are pointed out.

Single-file Brownian motion in periodic structures is an important process in nature and technology, which becomes increasingly amenable for experimental investigation under controlled conditions. To explore and understand basic features of this motion, the Brownian asymmetric simple exclusion process (BASEP) was recently introduced. In this BASEP, hard rods are driven by a constant drag force through a periodic potential with an amplitude much larger than the thermal energy. Here we derive general properties of the collective dynamics in the BASEP, discuss its connection to single-file transport by traveling wave potentials, and give a complete description of currents in steady states for all particle densities and diameters. For the open BASEP coupled to particle reservoirs, the nonequilibrium phases predicted by extremal current principles are verified by Brownian dynamics simulations. * dlips@uos.de †

A universal feature of single-file transport in micropores is the anomalous diffusion of a tracer particle. Here, we report on a new inherent property of the tracer dynamics in periodic free energy landscapes, which manifests itself in the kinetics of local transitions between neighboring energy minima: in the presence of a drift, transitions uphill against the drift are faster than along the more favorable downhill direction. The inequality between the uphill and downhill transition times holds for all densities and particle sizes. Dependent on the particle size, the transition times can be shorter or longer than the corresponding ones for a single particle. We provide a clear physical interpretation of these behaviors and show how they appear in various regimes of collective dynamics. Our findings provide a new robust method to probe collective effects by measurements of local tracer dynamics. They moreover demonstrate the complexity of extending Kramers’ diffusion model to an interacting many-body system.

Abstract. We propose a simple conjecture for the functional form of the asymptotic behavior of work distributions for driven overdamped Brownian motion of a particle in confining potentials. This conjecture is motivated by the fact that these functional forms are independent of the velocity of the driving for all potentials and protocols, where explicit analytical solutions for the work distributions have been derived in the literature. To test the conjecture, we use Brownian dynamics simulations and a recent theory developed by Engel and Nickelsen (EN theory), which is based on the contraction principle of large deviation theory. Our tests suggest that the conjecture is valid for potentials with a confinement equal to or weaker than the parabolic one, both for equilibrium and for nonequilibrium distributions of the initial particle position. For potentials with stronger confinement, the conjecture fails and gives a good approximate description only for fast driving. In addition we obtain a new analytical solution for the asymptotic behavior of the work distribution for the V-potential by application of the EN theory, and we extend this theory to nonequilibrated initial particle positions.

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