Variational approach to shape coexistence in 56Ni Original Research Article

Results are presented concerning shape coexistence and neutron–proton correlations at low and high spins in the N=Z nucleus 56Ni obtained within the complex version of the Excited Vampir variational approach. The coexistence of small and moderately deformed oblate and prolate configurations, strongly mixed in some cases, may explain the irregularities observed for the yrast line, as well as the presence of other nonyrast states connected with them by E2 or Ml transitions. The first deformed band is well reproduced and predictions on the structure of next deformed bands are presented. These are the first microscopic calculations for 56Ni including in the model space the View the MathML source and View the MathML source spherical orbitals besides the full pf-shell. Contaminations due to the center of momentum motion are discussed and a rough method to eliminate them at least approximately is presented.