WIAS Preprint No. 1032, (2005)

Micro-macro transitions in the atomic chain via Whitham's modulation equation


  • Dreyer, Wolfgang
  • Herrmann, Michael
  • Mielke, Alexander
    ORCID: 0000-0002-4583-3888

2010 Mathematics Subject Classification

  • 37K60 70F45 70K70 74A25 82C21


  • atomic chain, traveling waves, thermodynamic limit, modulation theory


The subject matter of this paper is the thermodynamic description of the nonlinear atomic chain with temperature. For this reason we consider special approximate solutions of Newton's equations, in which the atoms perform microscopic oscillations in form of modulated traveling waves. We start with an existence result for periodic traveling wave with arbitrary large amplitudes, and study several examples including the harmonic chain, the hard sphere model, and the small-amplitude approximation. Then we discuss the thermodynamic properties of traveling waves, and derive the corresponding Gibbs equation. Afterwards we focus on the macroscopic evolution of modulated traveling waves. For this purpose we apply Whitham's modulation theory to the atomic chain, and derive the modulation equation, which turns out to be a system of four macroscopic conservation laws. The last part is devoted to the justification problem: We state a conjecture for the general case, and prove this conjecture for the harmonic chain and the hard sphere model.

Appeared in

  • Nonlinearity, 19 (2006) pp. 471--500.

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