Effects of deformation in the three-body structure of Li11

Abstract Li 11 is studied within a three-body model Li 9 + n + n where the core is allowed to be deformed and/or excite. In particular, we include reorientation couplings and couplings between the two bound states of Li 9 . Contrary to the other examples studied within this model, we find that core excitation does not affect the structure of Li 11 significantly. Reorientation couplings of the deformed Li 9 can change the ground state of Li 11 from a predominantly two neutron ( s 1 / 2 ) 2 configuration into a ( p 1 / 2 ) 2 . A comparison with shell model results based on the WBP Hamiltonian is presented. The largest difference between the two models is that the d 2 occupancy is 7–10% for the three-body model versus 20% for the shell model.