Description of the 56Ni ground state with a few symmetry projected general complex Hartree–Fock–Bogoliubov determinants

Abstract

The ground state of the mid pf-shell nucleus 56Ni is described in the framework of a symmetry-projected complex mean-field theory in which the desired symmetry properties are exactly projected from the most general Hartree–Fock–Bogoliubov type determinants. This few determinant method is applied for the first time in a full 1 p0 f-shell model space. In the calculations the FPD6 effective interaction was used. It turns out that the use of only a few such generalized determinants is sufficient to give an excellent result. We compare the result with that of the quantum Monte Carlo approach, as well as with recently performed exact shell-model diagonalizations.