The energy levels of the even-even Ge isotopes with mass number between 64 and 78 are studied in the model of the traditional interacting boson approximation. To account for the multiple band structure of these isotopes, one boson is allowed to break and form a fermion pair. The two fermions are allowed to excite to ${\mathit{f}}_{5/2}$ and ${\mathit{g}}_{9/2}$ single-particle orbitals. It was found that the energy levels of the ${}_{}{}^{64–78}{}_{}{}^{}\mathrm{Ge}$ isotopes can be reproduced reasonably.

• Received 4 December 1991

DOI:https://doi.org/10.1103/PhysRevC.46.195