Intermittent many-body dynamics at equilibrium
Campbell, D. K.
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Citation (published version)C. Danieli, D.K. Campbell, S. Flach. 2017. "Intermittent many-body dynamics at equilibrium." PHYSICAL REVIEW E, Volume 95, Issue 6, 5 pp. https://doi.org/10.1103/PhysRevE.95.060202
The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body system. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. Long excursions arise from sticky dynamics close to q-breathers localized in normal mode space. Measuring the exponent allows one to predict the transition into nonergodic dynamics. We generalize our method to Klein-Gordon lattices where the sticky dynamics is due to discrete breathers localized in real space.
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