The Anti-FPU Problem

Abstract : We present a detailed analysis of the modulational instability of the zone-boundary mode for one and higher-dimensional Fermi-Pasta-Ulam (FPU) lattices. Following this instability, a process of relaxation to equipartition takes place, which we have called the Anti-FPU problem because the energy is initially fed into the highest frequency part of the spectrum, at variance with the original FPU problem (low frequency excitations of the lattice). This process leads to the formation of chaotic breathers in both one and two dimensions. Finally, the system relaxes to energy equipartition on time scales which increase as the energy density is decreased. We show that breathers formed when cooling the lattice at the edges, starting from a random initial state, bear strong qualitative similarities with chaotic breathers.
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Contributeur : Thierry Dauxois <>
Soumis le : mardi 16 octobre 2007 - 22:02:14
Dernière modification le : jeudi 19 avril 2018 - 14:54:03

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Thierry Dauxois, Ramaz Khomeriki, Francesco Piazza, Stefano Ruffo. The Anti-FPU Problem. Chaos, American Institute of Physics, 2005, 15 (1), pp.015110. 〈ensl-00179880〉



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