An Alternative Description of the Prolate-Oblate Shape Phase Transition in the Interacting Boson Model

The prolate-oblate shape phase transition in the interacting boson model is investigated for finite N as well as in the large-N classical limit by adopting the Hamiltonian with a linear dependence on the control parameter. The results indicate that the critical dynamics in the new scheme is of the γ-soft type similar to the O(6) dynamics. It is also shown that the structural evolution in the Hf-Hg mass region can be well reproduced in the present scheme.