Improved basis selection for the projected configuration interaction method applied to medium-heavy nuclei

Physical Review C (Impact Factor: 3.88). 09/2009; 80(3). DOI: 10.1103/PhysRevC.80.034325
Source: arXiv

ABSTRACT In a previous paper, we proposed a projected configuration interaction method that uses sets of axially deformed single-particle states to build up the many-body basis. We show that the choice of the basis set is essential to the efficiency of the method, and we propose a newly improved algorithm for selecting the projected basis states. We also extend our method to model spaces that can accommodate both parities and can include odd-multipole terms in the effective interaction, such as the octupole contributions. Examples of Ni56, Se68, Se70, and Se76 are calculated showing good agreement with the full configuration interaction results.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Half-lives T1/22nu for two-neutrino positron double beta decay modes beta+EC/ECEC are calculated for 84Sr, a nucleus of current experimental interest, within the framework of the deformed shell model based on Hartree-Fock states employing a modified Kuo interaction in (2p3/2, 1f5/2, 2p1/2, 1g9/2) space. For a reasonable description of the spectra of 84Sr and 84Kr and to generate allowed GT strengths, the single particle energies of the proton and neutron 1g9/2 orbitals, relative to the 2p3/2 orbital energy, are chosen to be 3.5 MeV and 1.5 MeV for both 84Sr and 84Rb and 1.5 MeV and 1.5 MeV for 84Kr. With this, the calculated half-lives for the beta+EC and ECEC modes are 1026 yr and 4×1024 yr respectively.
    International Journal of Modern Physics E 08/2011; 20(8):1723-1733. DOI:10.1142/S021830131101957X · 0.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate how the energy-variance extrapolation method works using the sequence of the approximated wave functions obtained by the Monte Carlo Shell Model (MCSM), taking 56Ni with pf-shell as an example. The extrapolation method is shown to work well even in the case that the MCSM shows slow convergence, such as 72Ge with f5pg9-shell. The structure of 72Se is also studied including the discussion of the shape-coexistence phenomenon.
    AIP Conference Proceedings 05/2011; 1355:138-144. DOI:10.1063/1.3584057
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new algorithm for calculating the spin- and parity-dependent shell model nuclear level densities using the moments method in the proton-neutron formalism will be presented. A new, parallelized code based on this algorithm was developed and tested using up to 4,000 cores on FRANKLIN/NERSC, for a set of nuclei from the sd-, pf-, and pf+g9/2- model spaces. By comparing the low excitation energy nuclear level densities for a given nucleus calculated in two model spaces, such as pf and pf+g9/2, we could estimated its ground state energy in the larger model space, which is not accessible to direct shell model calculations because of the unmanageable dimension. Examples for the ground state energies of for ^64Ge and ^68Se in the pf+g9/2 model space will be presented. )
    Physical Review C 04/2010; 82(2). DOI:10.1103/PhysRevC.82.024304 · 3.88 Impact Factor


Available from