The $\mathrm{sdg}$ interacting-boson model is applied to ${}_{}{}^{168}{}_{}{}^{}\mathrm{Er}$. Energy levels and $E2\mathrm{}$ transitions are calculated. This model is shown to solve the problem of anharmonicity regarding the excitation energy of the first $K^{\pi }=4^{+}$ band relative to that of the first $K^{\pi }=2^{+}$ one. The level scheme including the $K^{\pi }=3^{+}$ band is well reproduced and the calculated $B\left(E2\mathrm{}\right)\mathrm{}$'s are consistent with the experimental data.

• Received 4 November 1985

DOI:https://doi.org/10.1103/PhysRevLett.56.1116