Figure 1

Velocity and diffusion coefficient (9) vs tilt $F$ for a dimer $(N=2)$, satisfying (2) with (8, 26), $\eta =T=L=1$, $\Delta U=10$, vanishing equilibrium interparticle separation $(a=0)$, and different values of the coupling constant $\kappa$. According to (27), the critical tilt is $F_c=31.4\dots$. Dashed lines: Analytical results (14) for asymptotically small $\kappa$. Solid lines: Analytical results (22) for asymptotically large $\kappa$. Filled and empty circles: Numerical results for $\kappa =100$ and 200, respectively. The numerical uncertainty is quantified by the small erratic deviations from a smooth behavior. For still smaller and larger $\kappa$ values (not shown), the numerically obtained results approach the corresponding analytical asymptotics.Reuse & Permissions

Figure 2

Velocity and diffusion coefficient vs coupling constant $\kappa$ for the same system as in Fig. 1 with a fixed tilt $F=22$ and a dimer rest length of $a=0$ (filled circles) and $L∕2$ (empty circles). Horizontal lines correspond to the analytical results for asymptotically small and large $\kappa$ from (14, 22), respectively. The inset in (a) shows the velocity for $a=0$ together with the results of the analytic approximation (29).Reuse & Permissions

Figure 3

Model of dimer motion in a tilted periodic potential.Reuse & Permissions

Figure 4

(Color online) (a) Mobility $v∕F$ and (b) diffusion coefficient $D$ from (22) for a system of $N=5$ rigidly coupled Brownian particles vs equilibrium interparticle separation $a$ at different values of the tilt $F$. Solid red line, $F=4$; dashed green line, $F=7$; dotted blue line, $F=10$; dash-dotted cyan line, $F=35$. In (b), the solid black curve corresponds to the diffusion coefficient at zero tilt, $F=0$. All other parameter values are the same as in Fig. 1. (c) The critical force (30) corresponding to the effective potential (19). The four horizontal lines correspond to the above specified four values of the applied bias $F$.Reuse & Permissions