α clustering and superdeformation of ²⁸Si

¹ RIKEN Nishina Center for Accelerator-Based Science, RIKEN, Wako 351-0198, Japan
² Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan
³ Creative Research Initiative “Sousei,” Hokkaido University, Sapporo 001-0021, Japan

^a e-mail: yasutaka@riken.jp

Abstract

We have studied positive-parity states of ²⁸Si using antisymmetrized molecular dynamics and multiconfiguration mixing with constrained variation. Applying constraints to the cluster distance and the quadrupole deformation of the variational calculation, we have obtained basis wave functions that have various structures such as α-²⁴Mg and ¹²C-¹⁶O cluster structures as well as deformed structures. Superposing those basis wave functions, we have obtained a oblate ground state band, a β vibration band, a normal-deformed prolate band, and a superdeformed band. It is found that the superdeformed bands contain large amounts of the α-²⁴Mg cluster components. The results also suggest the presence of two excited bands with the developed α-²⁴Mg cluster structure, where the inter-cluster motion and the ²⁴Mg-cluster deformation play important roles.