Octupole correlations in superdeformed bands of ${}^{56}$Ni

Abstract

The projected multi-dimensionally-constrained relativistic Hartree-Bogoliubov model was employed to calculate the potential energy surface of the high-spin states in ${}^{56}\text{Ni}$. It is pointed out for the first time that possible octupole deformations exist for the positive and negative parity superdeformed bands in ${}^{56}\text{Ni}$, with deformations ${\beta }_{30}\sim 0.14$ and ${\beta }_{30}\sim 0.24$, respectively, along with a large prolate deformation of ${\beta }_{20}\sim 0.42$. These octupole deformations are induced by the coupling between $2p_{3/2}$ and $1g_{9/2}$ orbits at the deformation ${\beta }_{20}\sim 0.4$. The calculated excitation energies of the two rotational bands are consistent with the observed superdeformed bands of ${}^{56}\text{Ni}$. In addition, two rotational bands are predicted, consisting of one superdeformed band with negative parity and one hyperdeformed bands with positive parity.

Comments: 9 pages, 7 figures