Gao, ZC (reprint author), China Inst Atom Energy, Beijing 102413, Peoples R China.
We implemented a variation after projection (VAP) algorithm based on a triaxially deformed Hartree-Fock-Bogoliubov vacuum state. This is the first projected mean field study that includes all the quantum numbers (except parity), i.e., spin (J), isospin (T), and mass number (A). Systematic VAP calculations with JTA projection have been performed for the even-even sd-shell nuclei with the USDB Hamiltonian. All the VAP ground state energies are within 500 keV above the exact shell model values. Our VAP calculations show that the spin projection has two important effects: (1) the spin projection is crucial in achieving good approximation of the full shell model calculation; (2) the intrinsic shapes of the VAP wave functions with spin projection are always triaxial, while the Hartree-Fock-Bogoliubov methods likely provide axial intrinsic shapes. Finally, our analysis suggests that one may not be possible to associate an intrinsic shape to an exact shell model wave function.
National Natural Science Foundation of China [11175258, 11575290, 11321064, 11275068]
; CUSTIPEN (China-US Theory Institute for Physics with Exotic Nuclei) under US DOE [DE-FG02-13ER42025]
; State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China [Y5KF141CJ1]
; National Science Foundation [PHY-1404442]