{
  "abstract": "Hydrogen-rich materials offer a route to high-temperature conventional superconductivity, but often require extreme pressures. Here we report a first-principles study of NaH$_6$, identified in our large-scale hydride search and independently predicted in a subsequent high-throughput study. Several phases compete, with $R\\bar{3}m$ and $Pm\\bar{3}m$ dominant over broad pressure ranges. The $R\\bar{3}m$ phase remains dynamically stable down to 10 GPa, where its calculated $T_\\mathrm{c}$ is 34 K, rising to 99 K at 50 GPa. Cubic $Pm\\bar{3}m$ becomes thermodynamically competitive at higher pressures and reaches a calculated $T_\\mathrm{c}$ of 230 K at 50 GPa, decreasing only weakly upon further compression. Molecular dynamics and phonon-renormalization calculations support structural persistence over the sampled timescale and indicate relatively small anharmonic effects. Despite their high $T_\\mathrm{c}$, both phases contain elongated H$_2$-like units, often considered unfavorable for high-$T_\\mathrm{c}$ hydrides. Mode-resolved electron-phonon coupling links Raman-active hydrogen vibrations to superconductivity. In $R\\bar{3}m$, the linewidths of these modes increase with the pressure-induced tilt of H$_2$ units relative to the threefold axis, alongside the rise in $T_\\mathrm{c}$. A minimal symmetry-based model of the vibration-induced second-moment tensor of the hydrogen sublattice shows that these trends are consistent with a significant contribution from response components perpendicular to the threefold axis. NaH$_6$ thus represents an unusual molecular-like hydride in which hydrogen-sublattice reorganization may enable high-$T_\\mathrm{c}$ superconductivity at comparatively moderate pressures.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.17148",
  "author_total": 2,
  "authors": [
    {
      "name": "Tianran Chen"
    },
    {
      "name": "Taner Yildirim"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7rsyr985vsbq3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.17148",
  "fulltext_url": null,
  "id": "7rsyr985vsbq3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.17148",
  "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.supr-con"
    ],
    [
      "openalex",
      "1908|High-pressure geophysics and materials"
    ]
  ],
  "openalex": "W7221835371",
  "pdf_url": "https://arxiv.org/pdf/2610.17148",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-12",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7rsyr985vsbq3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:06Z",
      "native_id": "2610.17148",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.17148"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.supr-con",
      "subfield": "condensed-matter"
    }
  ],
  "title": "H$_2$-Like Units and Pressure-Tunable High-$T_\\mathrm{c}$ Superconductivity in NaH$_6$",
  "title_text": "H_2-Like Units and Pressure-Tunable High-T_c Superconductivity in NaH_6",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:06Z",
  "url": "https://research.draconitic.com/paper/7rsyr985vsbq3",
  "venue": "arXiv",
  "versions": []
}