We present results for summed orbital $1^{+}$ strengths in Sm and Nd isotopes obtained from deformed Hartree-Fock+BCS calculations, using a microscopic formulation of the scissors mode (the PHFB model) that excludes spurious contributions. It is found that the calculated $1^{+}$ strengths for the two chains of isotopes are proportional to ${\mathrm{\delta }}^2$ and that the summed strengths up to 4 MeV are in fair agreement with experimental data. It is also found that when pairing is neglected the total scissors mode strength is proportional to δ rather than to ${\mathrm{\delta }}^2$. Analytical expressions are given for the explicit dependence on the deformation parameter with and without pairing, valid for the anisotropic harmonic oscillator model.

• Received 16 July 1991

DOI:https://doi.org/10.1103/PhysRevC.44.R1250