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DY: Fachverband Dynamik und Statistische Physik

DY 22: Posters I

DY 22.44: Poster

Mittwoch, 28. März 2012, 17:00–19:00, Poster A

Nonlinear Dynamics of Coupled Oscillators with Localized Energy Dissipation — •Rita Leite and Lutz Schimansky-Geier — Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin

In this work we investigate the thermally activated transition dynamics of a harmonically coupled one-dimensional oscillator chain. In contrast to previous work [Henning et al., EPL (2007)], in which the collective escape dynamics of purely deterministic system initiated/supported by modulation instability (Breathers) [Dauxois et al., Phys. Rev. Lett., Vol. 70 (1993)] has been considered, in our model, the oscillator chain is coupled to an external heat bath. The latter is modeled by a single Brownian particle evolving a purely harmonic on-site potential. The units of the oscillator chain evolve/are located in a one-dimensional, nonlinear, asymmetric on-site potential and they are not affected by the effects of damping and noise.
Depending on the chosen boundary conditions (open or periodic boundary conditions), we observe a resonance behavior of the average crossing time as a function of the coupling strength κ. In the weak coupling limit the fluctuations of the heat bath are only weakly transferred to the chain and consequently crossing events are rare. With increasing coupling the system is thermalized rapidly, resulting in a minimum of the average crossing time. The latter increases proportional to e^κ with further growing coupling strength. Spatially localized modulation instability can not be detected in this model for the chosen anharmonicity parameter and fluctuation strength.