A systematic study of the superdeformation of Pb isotopes with   relativistic mean field theory
  The microscopically constrained relativistic mean field theory is used to investigate the superdeformation for Pb isotopes. The calculations show that there exists a clear superdeformed minimum in the potential energy surfaces with four different interactions NL3, PK1, TM1 and NLSH. The excitation energy, deformation and depth of well in the superdeformed minimum are comparable for four different interactions. Furthermore the trend for the change of the superdeformed excitation energy with neutron number is correctly reproduced. The calculated two-neutron separation energy in the ground state and superdeformed minimum together with their differences are in agreement with the data available. The larger energy difference appearing in superdeformed minimum reflects a lower average level density at superdeformations for Pb isotopes. 
Jian-You Guo, Zong-Qiang Sheng, Xiang-Zheng Fang