Structures and Transitions in Light Unstable Nuclei

We study the structures of the unstable Be isotopes with the theoretical method of antisymmetrized molecular dynamics. It is found that various structures of the excited states appear in the low-energy region of neutron-rich Be nuclei. Focusing on the 2$\alpha$ clustering, we analyze the intrinsic structures with the help of the experimental data of Gamow-Teller transitions.