Analyzing chaos in higher order disordered quartic-sextic Klein-Gordon lattices using q-statistics

Chris G. Antonopoulos, Charalampos Skokos, Tassos Bountis, Sergej Flach

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


In the study of subdiffusive wave-packet spreading in disordered Klein–Gordon (KG) nonlinear lattices, a central open question is whether the motion continues to be chaotic despite decreasing densities, or tends to become quasi-periodic as nonlinear terms become negligible. In a recent study of such KG particle chains with quartic (4th order) anharmonicity in the on-site potential it was shown that q−Gaussian probability distribution functions of sums of position observables with q > 1 always approach pure Gaussians (q=1) in the long time limit and hence the motion of the full system is ultimately “strongly chaotic”. In the present paper, we show that these results continue to hold even when a sextic (6th order) term is gradually added to the potential and ultimately prevails over the 4th order anharmonicity, despite expectations that the dynamics is more “regular”, at least in the regime of small oscillations. Analyzing this system in the subdiffusive energy domain using q-statistics, we demonstrate that groups of oscillators centered around the initially excited one (as well as the full chain) possess strongly chaotic dynamics and are thus far from any quasi-periodic torus, for times as long as t=109.

Original languageEnglish
Pages (from-to)129-134
Number of pages6
JournalChaos, Solitons and Fractals
Publication statusPublished - Nov 2017


  • Chaotic dynamics
  • Klein–Gordon
  • Quasi-periodic motion
  • Subdiffusive regime
  • Tsallis entropy
  • Wave packet spreading
  • q-Gaussian
  • q-statistics

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematics(all)
  • Physics and Astronomy(all)
  • Applied Mathematics

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