{
  "abstract": "We present an analytic response formalism for harmonic vibrational spectroscopy with the extended tight-binding (xTB) family of electronic-structure methods. A fieldspace coupled-perturbed self-consistent-charge treatment delivers molecular polarizabilities and, via the interchange theorem, analytic dipole derivatives (atomic polar tensors). Carrying the same formalism to nuclear perturbations yields closed-form analytic nuclear Hessians, which combine a metric-perturbed coupled-perturbed solve with explicit second-derivative terms built on dedicated integral kernels, and whose response weights carry the occupation and Fermi-level response of a Fermi-smeared reference, so that fractionally occupied and restricted odd-electron systems are treated in the same theory as closed shells. Combining the two first-order response sets in a mixed field–nuclear treatment then gives analytic polarizability derivatives (Raman tensors) without any second-order response solve. The formulation covers the GFN{0/1/2}xTB family, from the non-self-consistent GFN0-xTB to the anisotropic multipole electrostatics and self-consistent dispersion of GFN2-xTB, and is implemented on top of the public interfaces of the tblite library. All properties are validated against finitedifference references at their noise floor, and the response solves add only a small, diagonalization-free overhead to a converged calculation, so all three tensors of the double-harmonic infrared and Raman spectrum become available analytically at tightbinding cost.",
  "abstract_shown": true,
  "affiliations": [
    "Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, Heidelberg, Germany, 69120"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 2,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Philipp Pracht",
      "orcid": "0000-0002-8495-9504"
    },
    {
      "affs": [
        0
      ],
      "name": "Lukas S. Rindt",
      "orcid": "0009-0008-4474-4534"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c6dz9c8tqnmqw.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008278/v1",
  "fulltext_url": null,
  "id": "c6dz9c8tqnmqw",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008278/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|Advanced Chemical Physics Studies"
    ]
  ],
  "openalex": "W7208784846",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-03",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/c6dz9c8tqnmqw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:17Z",
      "native_id": "10.26434/chemrxiv.15008278",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008278/v1"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3107|Advanced Chemical Physics Studies",
      "subfield": "amo"
    }
  ],
  "title": "Coupled-perturbed extended tight-binding for analytic Hessians, infrared and Raman spectra",
  "title_text": "Coupled-perturbed extended tight-binding for analytic Hessians, infrared and Raman spectra",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:17Z",
  "url": "https://research.draconitic.com/paper/c6dz9c8tqnmqw",
  "venue": "ChemRxiv",
  "versions": []
}