Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 30: Nonlinear stochastic systems

DY 30.5: Talk

Friday, March 27, 2009, 11:15–11:30, ZEU 118

Transport of a dimer subject to localized forces over a periodic potential — •Steffen Martens, Dirk Hennig, and Lutz Schimansky-Geier — Institut für Physik, Humboldt-Universität zu Berlin

The overdamped Brownian motion of a dimer confined onto a periodic potential is studied. The two particles are coupled by non-linear interaction potentials, i.e., a Toda-like potential and the Morse potential. As extension of previous work [1,2] a localized dc force is applied to a one of the particles. The non-vanishing net current, instigated by thermal fluctuations and the localized point force, is quantitatively assessed by the value of the mobility of the center of mass. The latter is investigated both analytically and numerically. It turns out that the mobility of the dimer exhibits distinct properties in comparison with a monomer. In particular, the mobility as a function of the competing length scales of the system, that is the period of the substrate potential and the equilibrium distance between the two constituents, shows a resonance behavior. More precisely there exist a set of optimal parameter values maximizing the mobility. Further the net current is found to be a non-monotonous function of the localized driving force.

[1] D. Hennig, S. Martens, and S.Fugmann,Phys. Rev. E, 78, 011104, 2008.

[2] S. Martens, D. Hennig, S. Fugmann, and L. Schimansky-Geier, Phys. Rev. E, 78, 041121, 2008.