A microscopic method for analyzing the properties of even-even nuclei in terms of many interacting bosons is proposed. An exact boson image of the underlying shell-model Hamiltonian is derived and the dynamical behavior of the original fermion system is studied directly in the boson picture using the mean-field approximation. The resulting ideal boson states are shown to be free from the admixtures of spurious components, so that the cumbersome procedure of constructing the physical boson states can be avoided. The method is applied to calculating the energy spectra as well as the electron scattering form factors for the $0^{+}$→$0^{+}$ and $0^{+}$→$2^{+}$ transitions in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$. In all the cases under consideration, the agreement with experimental data is very good. The effect of the space truncation on the results is investigated as well.

• Received 11 January 1988

DOI:https://doi.org/10.1103/PhysRevC.38.1460