Similarity of nuclear structure in the ¹³²Sn and ²⁰⁸Pb regions: Proton-neutron multiplets

Starting from the striking similarity of proton-neutron multiplets in ¹³⁴Sb and ²¹⁰Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V_low-k approach. The calculated results for ¹³⁶Sb, ²¹²Bi, ¹³⁶I, and ²¹²At are in very good agreement with the available experimental data. The similarity between ¹³²Sn and ²⁰⁸Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.