{
  "abstract": "Deuteration can change which polymorph of a hydrogen-bonded crystal is stable. We derive a rule for the direction and size of this effect and test it across compounds. The H/D free-energy difference between two polymorphs is, to first order, ΔΔF ≈ S_str(1 − C)Δr̄, where Δr̄ is the difference in mean O-H length, S_str ≈ ½hc(1 − 1/ρ)s at room temperature comes from the softening s of the O-H stretch with bond length, and C is the fraction of the stretch term cancelled by bend and libration. While C < 1, deuteration favours the polymorph with the shorter O-H bonds, that is, with the weaker hydrogen bonds; where C(T) crosses unity the preference reverses. In harmonic calculations with three universal machine-learned potentials on 220 inorganic polymorph pairs, ΔΔF rises by 0.11 to 0.13 meV per H per mÅ at 300 K, with C about one half. For moderate to strong hydrogen bonds (a boundary chosen after inspecting the data) the rule is right in 74 of 84 pairs and 27 of 28 formulas; the exceptions share one Al(OH)₃ structure in which bend and libration outweigh the stretch at room temperature (C > 1 in two of the three models). The rule fails for weak hydrogen bonds and did not transfer in a prospective test on new pairs. Exploratory quasi-harmonic calculations put the diaspore to δ-AlOOH transition about 1 GPa higher for AlOOD than for AlOOH, a shift that high-pressure experiments can test.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "name": "Muhammet Can Erganiş"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/drzcqt7pfsp6n.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15011133/v1",
  "fulltext_url": null,
  "id": "drzcqt7pfsp6n",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011133/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",
      "1606|Crystallography and molecular interactions"
    ]
  ],
  "openalex": "W7224016594",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15011133/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/drzcqt7pfsp6n.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:26Z",
      "native_id": "10.26434/chemrxiv.15011133",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011133/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1606|Crystallography and molecular interactions",
      "subfield": "physical"
    }
  ],
  "title": "Deuteration favours the polymorph with shorter O-H bonds: a stretch-bend rule tested across 220 inorganic polymorph pairs",
  "title_text": "Deuteration favours the polymorph with shorter O-H bonds: a stretch-bend rule tested across 220 inorganic polymorph pairs",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:26Z",
  "url": "https://research.draconitic.com/paper/drzcqt7pfsp6n",
  "venue": "ChemRxiv",
  "versions": []
}