Importance of the hexadecapole-hexadecapole interaction

Motivated by the sensitivity of collective [Formula Presented] excitations to the hexadecapole-hexadecapole interaction, we explore the influence of this and other features of sdgIBM on the ground-state band properties of deformed rare-earth nuclei. We adopt microscopically motivated choices of the Hamiltonian parameters and work within the angular-momentum-projected intrinsic state formalism, deriving analytic expressions for observables in which the dependence on wave functions and parameters of the model is explicit. We find that energies of ground-state band excitations are insensitive to the hexadecapole-hexadecapole interaction. On the other hand, its contribution to the deformation energy term in the nuclear binding energy is substantial. Our results indicate that angular momentum projection is important even for well-deformed nuclei and that at least two g bosons should be utilized in the corresponding sdgIBM calculations.