{
  "abstract": "Time-resolved diffuse scattering from X-ray free-electron lasers and ultrafast electron diffraction gives access to the nonequilibrium lattice dynamics of photoexcited solids in reciprocal space. Existing interpretations have often relied on simplified models. Here we present a first-principles formulation of the time-dependent first-order diffuse intensity in which coherent and incoherent contributions emerge on equal footing. By assuming the probe-pulse coherence time to be longer than the characteristic electronic timescales, but shorter than those of the ionic motion, we work in the density-matrix formalism and derive equations of motion for the displacement-displacement correlators in a basis of instantaneous, out-of-equilibrium Born-Oppenheimer normal modes. We show how the incoherent contribution, governed by the phonon occupations, and a coherent contribution, governed by the anomalous phonon correlators, emerge. The non-trivial coherent dynamics is shown to be induced both by the photoinduced phonon-frequency shift and by electron-phonon scattering off the nonequilibrium carrier distribution. We implement the resulting equations using Wannier interpolation in the \\textsc{EPI}q code and apply them to photoexcited germanium. The calculated diffuse intensity reproduces both the oscillation frequencies and the rising incoherent background observed experimentally, opening the way to a systematic interpretation of time-resolved diffuse scattering in ultrafast experiments.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.22006",
  "author_total": 4,
  "authors": [
    {
      "name": "Matteo Furci"
    },
    {
      "name": "Giovanni Marini"
    },
    {
      "name": "Stefano Mocatti"
    },
    {
      "name": "Matteo Calandra"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fvkhxg74d39pv.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.22006",
  "fulltext_url": null,
  "id": "fvkhxg74d39pv",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.22006",
  "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",
      "3107|Laser-Matter Interactions and Applications"
    ]
  ],
  "openalex": "W7222453399",
  "pdf_url": "https://arxiv.org/pdf/2610.22006",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-15",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fvkhxg74d39pv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:50Z",
      "native_id": "2610.22006",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.22006"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Coherent and Incoherent Time-Resolved Diffuse Scattering Intensity from First Principles",
  "title_text": "Coherent and Incoherent Time-Resolved Diffuse Scattering Intensity from First Principles",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:50Z",
  "url": "https://research.draconitic.com/paper/fvkhxg74d39pv",
  "venue": "arXiv",
  "versions": []
}