The energy spacings of rotational levels in $K^{\pi }={\frac{3}{2}}^{-}$ bands in odd-neutron rare-earth nuclei are seen to exhibit an alternating behavior with the level spin. This behavior is analyzed empirically, phenomenologically, and theoretically. It is shown that the alternating term in phenomenological rotational energy expression is even more significant than the usual $I^2{\mathrm{}(I+1\mathrm{})\mathrm{}}^2$ correction term in most of the nuclei. Theoretical calculations employing Nilsson-model single-particle orbitals and including the contributions of admixtures from various $N=5\mathrm{}$ oscillator shell ${\mathrm{½}}^{-}$ single-particle states to perturb the rotational levels based on ${\frac{3}{2}}^{-}\mathrm{}\left[521\right]\mathrm{}$ states show that this behavior may reasonably be described as resulting from the third-order perturbation effects of the Coriolis interaction term in the Hamiltonian.

[NUCLEAR STRUCTURE Odd-$N$ even-$Z$ rare-earth nuclei, calculated Coriolis perturbation effects to $K=\frac{3}{2}$ rotational band levels.]

• Received 3 January 1974

DOI:https://doi.org/10.1103/PhysRevC.9.1965