Large-scale Nuclear Shell-Model Calculations of Isotopes in the Southwest Region of 208Pb

Large-scale nuclear shell-model calculations are performed in the neutron- and proton-deficient Pt, Au, Hg, and Tl isotopes ($Z < 82$ and $N \le 126$) near $^{208}$Pb. All the single-particle levels in the one-major shells, six neutron ($2p_{1/2}$, $1f_{5/2}$, $2p_{3/2}$, $0i_{13/2}$, $1f_{7/2}$, and $0h_{9/2}$) orbitals and five proton ($2s_{1/2}$, $1d_{3/2}$, $0h_{11/2}$, $1d_{5/2}$, and $0g_{7/2}$) orbitals are considered. For an effective two-body interaction, one set of the multipole pairing, quadrupole–quadrupole interactions is employed for all the nuclei considered. These phenomenological interactions are determined to reproduce the experimental energy spectra. Some of the isomeric states are analyzed in terms of the shell-model configurations. Octupole correlated states are discussed in terms of a collective octupole excitation on top of each shell model state.