{
  "abstract": "Oscillatory real-time integrals and the complete quadratic transformation between electronic-state normal modes are persistent obstacles in molecular internal-conversion calculations. We develop a finite-temperature Tyablikov–Moskalenko Green-function formulation that retains unequal frequencies, equilibrium displacement, Duschinsky rotation, the anomalous squeezing block, and a general first-order Herzberg–Teller nonadiabatic operator. The closed equations of motion reconstruct the vibronic correlation function by coupling-constant integration, while analytic continuation to complex time permits both a systematic saddle expansion and globally controlled integration on Lefschetz thimbles without numerical damping. For the 102-mode tetraoxa[8]circulene (4B) model at 300 K, the complete rate is 1.656× 10 7 s −1 at 18500 cm −1 . Herzberg–Teller coupling and Duschinsky rotation increase the rate by factors of approximately 2.45 and 2.06, respectively, while the squeezing contribution is about 46% in the mode-mixed calculation. The next-to-leading saddle result differs from the full thimble value by 0.66% at the molecular gap; one contributing thimble and no Stokes transition are found throughout 5000–35000 cm −1 . The same formalism gives aligned electric-and magnetic-field thresholds of 1.06 × 108 V m −1 and 41.6 T. The method therefore provides a fast, damping-free route to complete harmonic vibronic rates together with an explicit global test of the integration contour.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, Faculty of Science",
    "University of Helsinki"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Rashid Valiev",
      "orcid": "0000-0002-2088-2608"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7bj7stz3sa9yw.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15010092/v1",
  "fulltext_url": null,
  "id": "7bj7stz3sa9yw",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010092/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3107|Spectroscopy and Quantum Chemical Studies"
    ]
  ],
  "openalex": "W7220950094",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15010092/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/7bj7stz3sa9yw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "10.26434/chemrxiv.15010092",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010092/v1"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3107|Spectroscopy and Quantum Chemical Studies",
      "subfield": "amo"
    }
  ],
  "title": "Green-function thimbles for internal conversion",
  "title_text": "Green-function thimbles for internal conversion",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/7bj7stz3sa9yw",
  "venue": "ChemRxiv",
  "versions": []
}