  Exact numerical diagonalization of the Bohr Hamiltonian by SU(1,1)xSO(5)
methods is used to obtain detailed quantitative predictions for single-phonon
and multi-phonon excitations in well-deformed rotor nuclei. Dynamical gamma
deformation is found to significantly influence the predictions through its
coupling to the rotational motion. Basic signatures for the onset of rigid
triaxial deformation are obtained.
