{
  "abstract": "Three- and four-body reduced density matrices in the active space are required for second-order n-electron valence perturbation theory (NEVPT2) following complete active-space configuration interaction (CASCI) calculations. We developed an algorithm to generate these computationally demanding quantities by extending the pi-CASCI program, which is based on the graphical symmetric group approach (GSGA). A manually written prototype was subsequently optimized through AI-assisted code optimization, resulting in substantially improved performance.",
  "abstract_shown": true,
  "affiliations": [
    "Hokkaido University, 5 Nishi - 8 Kita, Kita-ku, Sapporo-shi, Hokkaido, Japan, 060-0808",
    "Information Technology Center",
    "Nagoya University",
    "Advanced HPC Promotion and Support Center, Research Organization for Information Science and Technology, 1-5-2 Minatojima-Minamicho, Chuo-ku, Kobe, Japan, 650-0047",
    "Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, 3-34-1 Nishi-ikebukuro, Toshima-ku, Tokyo, 171-8501",
    "Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Kiyoshi Tanaka"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Takahiro Katagiri"
    },
    {
      "affs": [
        3
      ],
      "name": "Tatsuya Nakano"
    },
    {
      "affs": [
        4,
        5
      ],
      "name": "Yuji Mochizuki",
      "orcid": "0000-0002-7310-5183"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2amcbw5bbp3vw.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009760/v1",
  "fulltext_url": null,
  "id": "2amcbw5bbp3vw",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009760/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": "W7215125737",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15009760/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/2amcbw5bbp3vw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:21Z",
      "native_id": "10.26434/chemrxiv.15009760",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009760/v3"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3107|Advanced Chemical Physics Studies",
      "subfield": "amo"
    }
  ],
  "title": "An Algorithm for computing Three- and Four-Body Density Matrices from CASCI Wavefunction and AI-Assisted Code Optimization",
  "title_text": "An Algorithm for computing Three- and Four-Body Density Matrices from CASCI Wavefunction and AI-Assisted Code Optimization",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:21Z",
  "url": "https://research.draconitic.com/paper/2amcbw5bbp3vw",
  "venue": "ChemRxiv",
  "versions": []
}