Tests of two-boson approaches forO16

Abstract

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.