Effect of configuration mixing on quadrupole and octupole collective states of transitional nuclei

A model is presented that simultaneously describes shape coexistence and quadrupole octupole collective excitations within a theoretical framework based on the nuclear density functional theory interacting boson model. An optimal interacting-boson Hamiltonian incorporates configuration mixing between normal intruder states, as well degrees of freedom, identified by means self-consistent mean-field calculations using universal energy pairing interaction, with constraints triaxial axially-symmetric freedom. illustrative application to transitional nuclei $^{72}$Ge, $^{74}$Se, $^{74}$Kr, $^{76}$Kr shows inclusion states significantly lower levels excited $0^+$ predicted low-lying positive-parity are characterized strong admixture nearly spherical, weakly deformed oblate, strongly prolate shapes. The negative-parity shown be dominated configurations.