Mean field study of the quadrupole-octupole degree of freedom in the spdf boson model

We present a mean field study of the quadrupole-octupole degree of freedom in collective nuclei within the framework of the spdf-boson model. For realistic choices of the Hamiltonian parameters, the ground state of the system is shown to remain axially symmetric, which considerably simplifies the mean field treatment. The critical point for the onset of octupole deformation in quadrupole deformed systems is identified in the parameter space and importance of the parity projection in this process is emphasized. A systematic survey of excitation energies and electric transitions for one-phonon states is given, which will provide useful guidance for detailed studies of negative parity states within the spdf-boson model.