Revised Formulation of the Phenomenological Interacting Boson Approximation

Previous interacting-boson-approximation studies of deformed nuclei have used different forms of the quadrupole operator in the Hamiltonian and $E2$ operators. A revised formalism is proposed which employs consistent operators and embodies a simpler Hamiltonian. It yields improved agreement with the data for deformed nuclei, a number of parameter-free predictions for transition regions, a specific form of the O(6) limit which agrees with that found empirically, and a closer relation to the neutron-proton version of the model, IBA-2.