Description of the Hexadecapole Deformation Parameter in the sdg Interacting Boson Model

The hexadecapole deformation parameter β₄ of the rare-earth and actinide nuclei is investigated in the framework of the sdg interacing boson model. An explicit relation between the geometric hexadecapole deformation parameter β₄ and the intrinsic deformation parameters ε₄ , ε₂ are obtained. The deformation parameters β₄ of the rare-earths and actinides are determined without any free parameter. The calculated results agree with experimental data well. It also shows that the SU(5) limit of the sdg interacting boson model can describe the β₄ systematics as well as the SU(3) limit.