The energy spectra and electromagnetic transition probabilities of the negative-parity yrast states in odd-$A$ Lu isotopes $\mathrm{}(Z=71\mathrm{})\mathrm{}$ are investigated systematically using the particle-rotor model and are compared with experimental data before and after the band crossing. It is noted that the moment of inertia of the core after the band crossing is as much a smooth function of the total angular momentum $I,$ as that before the band crossing and can be described by the $\mathrm{ab}$ formula. Appreciably different are the triaxial deformations before $\left(\sim -20°\right)$ and after $(\sim +10\mathrm{}°)$ the band crossing for ${}^{161,163,165}\mathrm{Lu},$ while they are more or less similar $\left(\sim -10°\right)$ for ${}^{167}\mathrm{Lu}$ determined from the calculation.

• Received 17 May 1999

DOI:https://doi.org/10.1103/PhysRevC.60.054305