{
  "annotation_id": "56ae7295-8ef4-4dd5-afb2-2746b93b2841",
  "date_created": "2026-03-02T18:02:44.913000Z",
  "date_modified": "2026-03-02T18:02:44.913000Z",
  "file_hash": "29c332d9a3bae67ff4dd942074a8331712068830e425370f71905df092d21489",
  "private": false,
  "record": {
    "abstract": "Considered is quantum tunnelling in anisotropic spin systems in a magnetic\nfield perpendicular to the anisotropy axis. In the domain of small field the\nproblem of calculating tunnelling splitting of energy levels is reduced to\nconstructing the perturbatio n series with degeneracy, the order of degeneracy\nbeing proportional to a spin value. Partial summation of this series taking\ninto account \u0027\u0027dangerous terms\u0027\u0027 with small denominators is performed and the\nvalue of tunnelling splitting is calculated with allowance for the first\ncorrection with respect to a magnetic field.",
    "arxiv_id": "quant-ph/9904064",
    "authors": [
      "V. V. Ulyanov",
      "O. B. Zaslavskii"
    ],
    "categories": [
      "quant-ph",
      "cond-mat.stat-mech",
      "hep-th"
    ],
    "doi": "10.1103/PhysRevB.60.6212",
    "journal_ref": "Phys.Rev.B60:6212,1999",
    "title": "Tunnelling series in terms of perturbation theory for quantum spin   systems",
    "url": "https://arxiv.org/abs/quant-ph/9904064"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "e7904f07-ef21-4aa6-8a2d-8ff8247aab56",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}