The approximations of the interacting boson approximation of Iachello and Feshbach and the ability of this approach to describe the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nucleus are tested. In the interacting boson approximation some "exchange" parts of many-boson matrix elements and violation of the Pauli principle in many-boson states are ignored. Matrix elements, two-boson wave functions and energies resulting from the interacting boson approximation are compared with exact two-hole two-particle calculations for the lowest 2+, 0 and the lowest excited 0+, 0 states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. It was found that neither of the above two approximations of the interacting boson approximation are valid. Calculations without these two approximations improve the approximate energies but not the wave functions.

NUCLEAR STRUCTURE ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$; calculated structure of lowest 0+ and 2+ excited levels. Interacting boson and shell model approaches.

• Received 21 March 1978

DOI:https://doi.org/10.1103/PhysRevC.18.2355