Jiao, CF (reprint author), Peking Univ, Sch Phys, State Key Lab Nucl Phys & Technol, Beijing 100871, Peoples R China.
For a shape-soft nucleus, the deformation change with increasing angular momentum of rotation can be significant. Total-Routhian-surface (TRS) calculations include the shape changes, but angular momentum is not conserved (neither is it a good quantum number, nor is it kept unchanged in the whole TRS mesh). In the projected shell model (PSM), the angular momentum appears as a good quantum number, but calculations have usually been performed with fixed deformation. In the present work, by performing angular-momentum projection on the mean-field potential-energy surface (PES), we can obtain an angular-momentum-conserved PES which gives deformation for a rotational state at a given spin. In order to investigate the shape-changing effect, we have chosen neutron-deficient Hg and Pb isotopes in which shape coexistence occurs. We interpret the irregular rotational behavior of the oblate bands at low spin as arising from deformation changes which are induced by collective rotation. At higher spin, the oblate rotational spectrum can also be influenced by the crossing between the K = 0 ground-state band and a low-K two-quasineutron band. Calculated g factors for the states of oblate bands are given for future experimental testing, and the intrinsic structures of high-K oblate states are investigated.
National Key Basic Research Program of China [2013CB83440]
; National Natural Science Foundation of China [11235001, 11320101004, 11205120]
; Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China [Y4KF041CJ1]
; UK Science and Technology Facilities Council [ST/J000051/1]