Low-energy dipole excitation mode in ${}^{18}$O with antisymmetrized molecular dynamics

Abstract

Low-energy dipole (LED) excitations in ${}^{18}$O were investigated using a combination of the variation after $K$-projection in the framework of antisymmetrized molecular dynamics with $\beta$-constraint with the generator coordinate method. We obtained two LED states, namely, the $1_1^{-}$ state with a dominant shell-model structure and the $1_2^{-}$ state with a large ${}^{14}\text{C}+\alpha$ cluster component. Both these states had significant toroidal dipole (TD) and compressive dipole (CD) strengths, indicating that the TD and CD modes are not separated but mixed in the LED excitations of ${}^{18}$O. This is unlike the CD and TD modes for well-deformed nuclei such as ${}^{10}$Be, where the CD and TD modes are generated as $K^{\pi }=0^{-}$ and $K^{\pi }=1^{-}$ excitations, respectively, in a largely deformed state.

19 pages, 7 figures

References in corpus (7)

• Exotic modes of excitation in atomic nuclei far from stability
• Decay Pattern of Pygmy States Observed in Neutron-Rich 26 Ne
• $\alpha$-cluster structure of ${}^{18}$O
• Cluster structures in Oxygen isotopes
• Tetrahedral $4\alpha$ and ${}^{12}\text{C}+\alpha$ cluster structures in ${}^{16}$O
• A variety of clustering in ${}^{18}$O
• Monopole and dipole transitions of the cluster states of 18O

Cited by in corpus (1)

• Low-energy dipole excitations in ${}^{20}$O with antisymmetrized molecular dynamics