Level spectra of Ni-isotopes with realistic interaction

Quasiparticle configuration-mixing calculations are made for the Ni-isotopes with an approximate reaction matrix of Hamada-Johnston potential reported by Kuo. The results are very close to those obtained by the exact shell-model calculations. But the agreement with the experimental spectra is poor in both these cases. A remarkable improvement is achieved in the quasiparticle results when the renormalized force strength and the quasiparticle quantities extracted by the inverse gap equation procedure are used. A possible further improvement in the inverse gap equation procedure is discussed.