We investigate microscopically systematic behavior of shape coexistence in even-even ${}^{106–120}\mathrm{Sn}$ isotopes in the framework of the shell model. The two-particle and two-hole (2p-2h) proton excitations across the $Z=50$ closed shell gap are essential to describe the deformed intruder states built on the first excited $0_2^{+}$ state, which intrudes into the spherical normal states, indicating the shape coexistence. In addition, the neutron excitations to the $1h_{11/2}$ orbit are important for a parabolic behavior of the intruder band with a minimum in the excitation energy near the neutron midshell $N=66$ point. The calculations predict that the crossing between the intruder and normal bands occurs between spin $I=4$ and $I=6$. From the potential energy surface (PES) with particle-number and angular-momentum projections, collective wave function, and quadrupole moments, it is shown that the calculations describe shape coexistence structure for the midshell Sn nuclei.

Close

PrevNext

View figure in article

• Nuclear reactions
• Nuclear structure & decays
• 90 ≤ A ≤ 149
• Collective models
• Models based on symmetries
• Nuclear many-body theory
• Shell model