The ${}^{66}\mathrm{Ge}$ and ${}^{68}\mathrm{Ge}$ nuclei are studied by means of the shell model with the extended $P+QQ$ Hamiltonian, which succeeds in reproducing experimentally observed energy levels, moments of inertia, and other properties. The investigation using the reliable wave functions predicts $T=0$,$J=9$ one-proton–one-neutron $\left(1p1n\right)$ alignment in the $g_{9∕2}$ orbit, at high spins (${14}_1^{+}$, ${16}_1^{+}$, and ${18}_1^{+}$) in these $N\approx Z$ even-even nuclei. It is shown that a series of the even-$J$ positive-parity yrast states (observed up to ${26}_1^{+}$ for ${}^{68}\mathrm{Ge}$) consists of the ground-state band and successive three bands with different types of particle alignments (two-neutron, $1p1n$, two-proton–two-neutron) in the $g_{9∕2}$ orbit.

• Received 9 April 2004

DOI:https://doi.org/10.1103/PhysRevC.70.031301