{
  "abstract": "We present an ab initio calculation of the band-to-band internal-conversion rate of the $\\hbarω_{\\rm nuc} \\approx 8.35$ eV isomeric transition in $^{229}$ThO$_2$. Because the nuclear transition energy exceeds the electronic band gap of ThO$_2$, the isomer can decay nonradiatively by resonantly promoting a valence electron into the conduction band. We formulate this process as a Brillouin-zone sum over vertical interband transitions weighted by local Th-centered hyperfine matrix elements, which are evaluated directly from all-electron full-potential linearized augmented-plane-wave Bloch spinors. A finite nuclear magnetization model is included to regularize the short-range hyperfine interaction and to account for the Bohr-Weisskopf effect. After applying scissor shifts to span the experimentally reported ThO$_2$ band gaps, we find calculated internal-conversion lifetimes in the range of $1-16~μ{\\rm s}$. The lifetime increases strongly as the band gap approaches $ω_{\\rm nuc}$ because the resonant interband phase space at the nuclear transition energy is reduced. For the larger reported ThO$_2$ gaps, the calculated lifetime is comparable to the measured conversion-electron Mössbauer lifetime [Nature 648, 300 (2025)]. Our analysis implies that choosing solid-state hosts with band-gap values slightly lower than $ω_{\\rm nuc}$ can optimize solid-state nuclear clock performance with internal-conversion electron readout.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2607.08941",
  "author_total": 6,
  "authors": [
    {
      "name": "Udeshika C. Perera"
    },
    {
      "name": "H. B. Tran Tan"
    },
    {
      "name": "H. W. T. Morgan"
    },
    {
      "name": "Eric Hudson"
    },
    {
      "name": "Daniel A. Rehn"
    },
    {
      "name": "Andrei Derevianko"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1j7tqxkgkgm4d.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.08941",
  "fulltext_url": null,
  "id": "1j7tqxkgkgm4d",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.08941",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "nucl-th"
    ],
    [
      "arxiv",
      "physics.atom-ph"
    ],
    [
      "openalex",
      "3107|Advanced Frequency and Time Standards"
    ]
  ],
  "openalex": "W7168184123",
  "pdf_url": "https://arxiv.org/pdf/2607.08941",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1j7tqxkgkgm4d.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2607.08941",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.08941"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.atom-ph",
      "subfield": "amo"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:nucl-th",
      "subfield": "nuclear"
    }
  ],
  "title": "Ab initio calculations of $^{229}$Th band-to-band internal conversion rate in $^{229}$ThO$_2$",
  "title_text": "Ab initio calculations of ^229Th band-to-band internal conversion rate in ^229ThO_2",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/1j7tqxkgkgm4d",
  "venue": "arXiv",
  "versions": []
}