2004/12/31 by C. Forssén, C. Forssen, P. Navratil +3 · 2 citations
Physics and Astronomy · #Atomic and Molecular Physics #Nuclear physics research studies #Quantum Chromodynamics and Particle Interactions #nucl-th
paper · pdf · doi:10.1103/physrevc.71.044312
published as Phys.Rev. C71 (2005) 044312 · 17 pages, 12 figures To be published in Phys. Rev. C Resubmitted version. Minor changes
arxiv created 2005/02/15 · openalex publication_date 2005/04/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We present the first ab initio structure investigation of the loosely bound 11Be nucleus, together with a study of the lighter isotope 9Be. The nuclear structure of these isotopes is particularly interesting because of the appearance of a parity-inverted ground state in 11Be. Our study is performed in the framework of the ab initio no-core shell model. Results obtained using four different, high-precision two-nucleon interactions, in model spaces up to 9\ensuremathℏ\ensuremathΩ, are shown. For both nuclei, and all potentials, we reach convergence in the level ordering of positive- and negative-parity spectra separately. Concerning their relative position, the positive-parity states are always too high in excitation energy, but a fast drop with respect to the negative-parity spectrum is observed when the model space is increased. This behavior is most dramatic for 11Be. In the largest model space we were able to reach, the 1/2+ level has dropped down to become either the first or the second excited state, depending on which interaction we use. We also observe a contrasting behavior in the convergence patterns for different two-nucleon potentials and argue that a three-nucleon interaction is needed to explain the parity inversion. Furthermore, large-basis calculations of 13C and 11B are performed. This allows us to study the systematics of the position of the first unnatural-parity state in the N=7 isotone and the A=11 isobar. The 11B run in the 9\ensuremathℏ\ensuremathΩ model space involves a matrix with dimension exceeding 1.1\ifmmode×\else\texttimes\fi109, and is our largest calculation so far. We present results on binding energies, excitation spectra, level configurations, radii, electromagnetic observables, and 10Be+n overlap functions.