{
  "abstract": "Electron-phonon interactions renormalize phonon frequencies and lifetimes and are central to the dynamical properties of solids. While these effects are usually described within linear electron-phonon coupling, the role of nonlinear electron-phonon interactions for phonon properties remains largely unexplored. In this work, we study phonon renormalization arising from the long-range linear one-electron-one-phonon and the nonlinear one-electron-two-phonon interactions within a diagrammatic framework. We derive the corresponding self-energy diagrams, which depend on the chemical potential and temperature, and evaluate them from first principles for the two polar semiconductors LiF and KTaO$_3$. In both materials, the two interaction channels renormalize the phonon spectrum in qualitatively distinct ways. The linear contribution is sharply localized near the Brillouin-zone center, whereas the nonlinear process couples an incoming phonon to other branches throughout the spectrum. As a result, it renormalizes phonons across the entire Brillouin-zone, with a pronounced temperature dependence governed by the thermal occupation of those branches. This behavior provides a clean experimental signature of the one-electron-two-phonon coupling. While the nonlinear phonon renormalization is small in LiF, it is somewhat larger in KTaO$_3$, which we attribute to its greater number of thermally populated phonon branches at room temperature. Our results establish a general framework to assess nonlinear electron-phonon effects on the phonon properties in materials with stronger lattice fluctuations, including soft semiconductors such as lead-halide perovskites.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.20639",
  "author_total": 6,
  "authors": [
    {
      "name": "Florian Kluibenschedl"
    },
    {
      "name": "Matthew Houtput"
    },
    {
      "name": "Jacques Tempere"
    },
    {
      "name": "Cesare Franchini"
    },
    {
      "name": "Mikhail Lemeshko"
    },
    {
      "name": "Ragheed Alhyder"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/70re1pc6r8may.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.20639",
  "fulltext_url": null,
  "id": "70re1pc6r8may",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.20639",
  "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.mtrl-sci"
    ],
    [
      "openalex",
      "3104|Physics of Superconductivity and Magnetism"
    ]
  ],
  "openalex": "W7213600113",
  "pdf_url": "https://arxiv.org/pdf/2609.20639",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-06",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/70re1pc6r8may.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:22Z",
      "native_id": "2609.20639",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.20639"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "First-principles theory of phonon renormalization from nonlinear electron-phonon interactions",
  "title_text": "First-principles theory of phonon renormalization from nonlinear electron-phonon interactions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:22Z",
  "url": "https://research.draconitic.com/paper/70re1pc6r8may",
  "venue": "arXiv",
  "versions": []
}