The scissor mode was applied to the yrast rotational band of the rare-earth even-even nuclei from ${}_{}{}^{152}{}_{}{}^{}\mathrm{Gd}$ to ${}_{}{}^{192}{}_{}{}^{}\mathrm{Os}$. The quadrupole deformations and backbending and forebending effects are well explained. This approach shows that the uppermost angular momentum of the G band exists and the superband and G band are made on the basis of the scissor mode. It is thought that this classical approach of the interacting boson model II can be reasonable in order to explain the low-lying energy levels of the rare-earth nuclei.

• Received 12 June 1990

DOI:https://doi.org/10.1103/PhysRevC.42.1380