A monopole-optimized effective interaction for tin isotopes

We present a systematic configuration-interaction shell model calculation on the structure of light tin isotopes with a new global optimized effective interaction. The starting point of the calculation is the realistic CD-Bonn nucleon-nucleon potential. The unknown single-particle energies of the $1d_{3\mathrm{/}2}$, $2s_{1\mathrm{/}2}$ and $0h_{11\mathrm{/}2}$ orbitals and the T=1 monopole interactions are determined by fitting to the binding energies of 157 low-lying yrast states in ${}^{102-132}$Sn. We apply the Hamiltonian to analyze the origin of the spin inversion between ${}^{101}$Sn and ${}^{103}$Sn that was observed recently and to explore the possible contribution from interaction terms beyond the normal pairing.