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DY: Fachverband Dynamik und Statistische Physik
DY 6: Poster Session I
DY 6.21: Poster
Montag, 22. März 2010, 16:00–18:00, Poster B2
Effect of negative resistance in the transport of a dimer system — •Steffen Martens1, Dirk Hennig2, and Lutz Schimansky-Geier1 — 1Department of Physics, TSP, Humboldt Universität zu Berlin, Newtonstrasse 15, 12489 Berlin, Germany — 2Department of Mathematics, University of Portsmouth, Lion Terrace, Portsmouth, Hampshire PO1 3HF
The one-dimensional as well as the two-dimensional overdamped Langevin dynamics of a dimer system consisting of two harmonically interacting components are studied. Both components are absorbed at the same spatially periodic substrate potential and are coupled to the same external heat bath. In contrast to previous works, we consider the impact of an inhomogeneous forcing, viz., an external localized point force applied at only one of the two components, on the dynamic of the dimer system. For the one-dimensional case, two accurate approximations for the center of mass mobility and its diffusion coefficient are obtained for weak and strong couplings. It turns out that the mobility of a dimer as a function of the competing length scales of the system, that are 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. Interestingly, while in the one-dimensional case the mobility as a function of the noise strength is a monotonic function of the latter in 2D we found the effect of negative resistance, i.e., the mobility possesses a minimum at a finite value of the noise strength for a given overcritical external force magnitude.