{
  "abstract": "In classical anharmonic lattices, the resonance structure driving nonlinear mode mixing is reshaped by band gaps. However, it remains unclear whether a spectral gap hinders or promotes long-time thermalization. Here we study a Fermi-Pasta-Ulam-Tsingou (FPUT) chain of equal masses joined by alternating dimensionless spring constants $1\\pmΔκ$, so that the chain is dimerized with strength $Δκ$, the classical vibrational analogue of the Su-Schrieffer-Heeger (SSH) model, and quantify how the acoustic-optical gap controls relaxation under $α$-type (cubic) nonlinearity. Tracking modal energies and spectral entropy via long-time symplectic simulations, we find that dimerization delays long-time relaxation. At $Δκ=1/2$, set by the onset of the first umklapp process that allows two zone-boundary acoustic phonons to fuse into a zone-center optical phonon, the three-wave acoustic-acoustic-optical channel closes. The effective acoustic-to-optical scattering rate reveals an interplay between the dynamic resonance vertex and the kinematic resonance manifold, which evolve differently with the dimerization parameter. Above the threshold $Δκ=1/2$, energy redistribution can nevertheless continue through higher-order resonances and quasiresonances. Yet specific boundary conditions and initial conditions can inhibit equipartition. These results identify the phononic gap as a tunable, momentum-selective filter for nonlinear energy transport, suggesting a general route to controlling energy transfer and equipartition in dimerized or topologically gapped nonlinear lattices and in flexible mechanical systems.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.09498",
  "author_total": 2,
  "authors": [
    {
      "name": "José A. Aké"
    },
    {
      "name": "Gerardo G. Naumis"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cvte3w4rv2k3a.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09498",
  "fulltext_url": null,
  "id": "cvte3w4rv2k3a",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.09498",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.stat-mech"
    ],
    [
      "openalex",
      "3109|Nonlinear Photonic Systems"
    ]
  ],
  "openalex": "W7212176099",
  "pdf_url": "https://arxiv.org/pdf/2609.09498",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cvte3w4rv2k3a.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2609.09498",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09498"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.stat-mech",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "Gap-controlled thermalization in a chain of alternating nonlinear springs: an SSH model version of the Fermi-Pasta-Ulam-Tsingou problem",
  "title_text": "Gap-controlled thermalization in a chain of alternating nonlinear springs: an SSH model version of the Fermi-Pasta-Ulam-Tsingou problem",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/cvte3w4rv2k3a",
  "venue": "arXiv",
  "versions": []
}