Recognition of SU(3)→O(6) Quantum Phase Transition in Groundstates of 156Gd Nucleus within Microscopic Theory

Key words: 
• quantum phase transition /
• evolution of groundstate structure /
• microscopic sdIBM-max approach /
• 156Gd nucleus

Abstract: The γray energy over spin curves identifies that there are the SU(3) and O(6) symmetries in the groundstates of the ¹⁵⁶Gd nucleus; by means of the microscopic sdIBMmax approach and signalparticle experimental energies the spectra of those two symmetries and their transient process are successfully reproduced through two parameters of nucleonnucleon effective interaction with pairing plus quadrupole pairing plus quadrupolequadrupole forces. The calculated results reveal a new way to recognize groundstates quantum phase transition, in which the basicstate of the SU(3) symmetry is a lowlying and lowordered state, while one of the O(6) are a highlying and highordered state, their critical region is between 6+1—8+1 states, the highordered basicstate releases spare orderedstructure energy, reducing rotationspeed, thus causing the restructure of lowordered basicstate and accomplishing the quantum phase transition from the highordered phase into the lowordered phase, the shape phase transition takes place along the yrast line of nucleus when it deexcited to the critical region. Because the structural phase transition takes place by noobvious charge of boson structure constants in the critical region it is a benignancy and calm transition with respect to its macroscopic behave. The potential energy surface of 156Gd nucleus has been illustrated to visualize.