Regensburg 2007 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 28: Nonlinear stochastic systems

DY 28.4: Vortrag

Donnerstag, 29. März 2007, 14:45–15:00, H2

Cooperative escape dynamics of an oscillator chain under microcanonical conditions — •Simon Fugmann, Dirk Hennig, and Lutz Schimansky-Geier — Institut fuer Physik, Humboldt Universitaet zu Berlin, Newtonstrasse 15, 12489 Berlin, Deutschland

We consider the self-organized escape of a chain of coupled oscillators from a metastable state over an energetic barrier. The underlying dynamics is conservative and deterministic. Supply of sufficient total energy or application of external forces brings the chain into the nonlinear regime from which an initially almost uniform lattice state becomes unstable and nonlinear redistribution leads to strong localization of energy. A spontaneously emerging critical localized mode grows to the unstable transition state and the chain, passing through the latter, performs a collective escape process over the barrier. It turns out that this nonlinear barrier crossing in a microcanonical situation is more efficient compared with a thermally activated chain for small ratios between the total energy of the chain and the barrier energy.