The coherent state model is extended so that three negative parity bands are treated on equal footing with three positive parity bands. The six rotational bands are generated by projecting out angular momenta and parities from three intrinsic orthogonal states which exhibit both quadrupole and octupole deformations. The projected states are, by construction, mutually orthogonal. In the space of projected states, a subspace of quadrupole and octupole multiboson states, an effective quadrupole and octupole boson Hamiltonian is solved. The eigenstates of the model Hamiltonian are linked by multipole transition operators for which lowest order boson expressions are considered. The calculations involve six structure coefficients and two deformation parameters. All of them are fixed by a least square fit of the known experimental energies. Applications are made to ${}^{158}\mathrm{Gd},$ ${}^{172}\mathrm{Yb},$ ${}^{218}\mathrm{Ra},$ ${}^{226}\mathrm{Ra},$ ${}^{232}\mathrm{Th},$ ${}^{238}\mathrm{U},$ and ${}^{238}\mathrm{Pu}.$ Results for excitation energies and transition probabilities are compared with the corresponding data. New signatures for octupole deformation, manifested in excited bands, are pointed out.

• Received 11 July 2001

DOI:https://doi.org/10.1103/PhysRevC.65.064322