{
  "annotation_id": "2d413f95-5245-4a36-9ff5-a2c7747ce584",
  "date_created": "2026-03-02T18:00:03.736000Z",
  "date_modified": "2026-03-02T18:00:03.736000Z",
  "file_hash": "85278d4a66bba683209ef67c10bb3d8d014d8f07afdc68114e83f2e9b8b2c4ed",
  "private": false,
  "record": {
    "abstract": "We are presenting the first ab initio structure investigation of the loosely\nbound 11-Be nucleus, together with a study of the lighter isotope 9-Be. The\nnuclear structure of these isotopes is particularly interesting due to the\nappearance of a parity-inverted ground state in 11-Be. Our study is performed\nin the framework of the ab initio no-core shell model. Results obtained using\nfour different, high-precision two-nucleon interactions, in model spaces up to\n9\\hbar\\Omega, are shown. For both nuclei, and all potentials, we reach\nconvergence in the level ordering of positive- and negative-parity spectra\nseparately. Concerning their relative position, the positive-parity states are\nalways too high in excitation energy, but a fast drop with respect to the\nnegative-parity spectrum is observed when the model space is increased. This\nbehavior is most dramatic for 11-Be. In the largest model space we were able to\nreach, the 1/2+ level has dropped down to become either the first or the second\nexcited state, depending on which interaction we use. We also observe a\ncontrasting behavior in the convergence patterns for different two-nucleon\npotentials, and argue that a three-nucleon interaction is needed to explain the\nparity inversion. Furthermore, large-basis calculations of 13-C and 11-B are\nperformed. This allows us to study the systematics of the position of the first\nunnatural-parity state in the N=7 isotone and the A=11 isobar. The 11-B run in\nthe 9\\hbar\\Omega model space involves a matrix with dimension exceeding 1.1 x\n10^9, and is our largest calculation so far. We present results on binding\nenergies, excitation spectra, level configurations, radii, electromagnetic\nobservables, and 10-Be+n overlap functions.",
    "arxiv_id": "nucl-th/0412049",
    "authors": [
      "C. Forssen",
      "P. Navratil",
      "W. E. Ormand",
      "E. Caurier"
    ],
    "categories": [
      "nucl-th"
    ],
    "doi": "10.1103/PhysRevC.71.044312",
    "journal_ref": "Phys.Rev. C71 (2005) 044312",
    "title": "Large basis ab initio shell model investigation of 9-Be and 11-Be",
    "url": "https://arxiv.org/abs/nucl-th/0412049"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "4bf1274b-6ebb-483b-b02b-0794a31daebf",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}