Multi-configuration mixing approach designed for large scale nuclear structure calculations

Abstract

A new program, which is an advanced stage in the numerical implementation of a specific family of nuclear structure models, is developed. In this approach a many-body Hamiltonian is diagonalized in the configuration space of general fully symmetry projected Hartree-Fock-Bogoliubov type quasiparticle determinants. The configurations are build on top of a mean-field solution of the Hartree-Fock-Bogoliubov problem with restoration of broken symmetries by projection before the variation of the wavefunction using the most general symmetry unrestricted quasi-particle transformation. In the approach, named GENERAL COMPLEX MONSTER the configuration space of the symmetry projected Hartree-Fock-Bogoliubov determinant is supplemented by all the symmetry projected 2-quasiparticle states build on top of this determinant. With this method a wide range of doubly-even, doubly-odd and odd nuclei can be treated on the same footing in comparatively large model spaces and a huge amount of states can be obtained. The involved mathematical tools and the solutions found to construct the code are presented. The implemented method was tested for the even 28Si and the odd 27Al nuclei from the middle of the 1s0d-shell. The new results are discussed and compared with the results of complete shell model diagonalizations.