{
  "annotation_id": "71487a8e-dfbd-4146-9e39-c6bff9303579",
  "date_created": "2026-03-02T18:00:39.425000Z",
  "date_modified": "2026-03-02T18:00:39.425000Z",
  "file_hash": "7031bbd5dfbbd081e750651b78ba1313746bb88346969c668528d18973db02af",
  "private": false,
  "record": {
    "abstract": "Fourth-order many-body corrections to matrix elements for atoms with one\nvalence electron are derived. The obtained diagrams are classified using\ncoupled-cluster-inspired separation into contributions from n-particle\nexcitations from the lowest-order wavefunction. The complete set of\nfourth-order diagrams involves only connected single, double, and triple\nexcitations and disconnected quadruple excitations. Approximately half of the\nfourth-order diagrams are not accounted for by the popular coupled-cluster\nmethod truncated at single and double excitations (CCSD). Explicit formulae are\ntabulated for the entire set of fourth-order diagrams missed by the CCSD method\nand its linearized version, i.e. contributions from connected triple and\ndisconnected quadruple excitations. A partial summation scheme of the derived\nfourth-order contributions to all orders of perturbation theory is proposed.",
    "arxiv_id": "physics/0204056",
    "authors": [
      "Andrei Derevianko",
      "Erik D. Emmons"
    ],
    "categories": [
      "physics.atom-ph"
    ],
    "doi": "10.1103/PhysRevA.66.012503",
    "title": "Fourth-order perturbative extension of the singles-doubles   coupled-cluster method",
    "url": "https://arxiv.org/abs/physics/0204056"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "c9b1c6a4-264d-42c7-8d16-f3ac3f4fb41c",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}