Effective interaction and energy levels of light and intermediate nuclei (${}_{}{}^6{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$, and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$) are calculated using the interaction of Shakin and his collaborators derived from the Yale potential following the unitary-model-operator approach. Detailed comparison is made with works of Kuo-Brown and other authors. It is found that the differences in the approximations used by different groups of workers in the evaluation of the reaction matrix elements can lead to large differences in the spectra, indicating that it is very necessary to evaluate the reaction matrix elements more precisely before applying them to nuclear-structure calculations.

• Received 29 May 1968

DOI:https://doi.org/10.1103/PhysRevC.3.1466