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

The hexadecapole deformation parameter β_(4) 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 β_(4) and the intrinsic deformation parametersε4,ε_(2) are obtained.The deformation parameters β_(4) 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 β_(4) systematics as well as the SU(3)limit.