Multipole modes of excitation in tetrahedrally deformed neutron-rich Zr isotopes

TL;DR

This study investigates multipole excitation modes in tetrahedrally deformed neutron-rich Zr isotopes using covariant density functional theory, revealing a unique peak as an indicator of tetrahedral shape.

Contribution

It introduces a novel method to identify tetrahedral deformation in Zr isotopes through specific excitation mode signatures.

Findings

A distinct peak at 9.0-10.0 MeV in isoscalar quadrupole strength for tetrahedral Zr isotopes.

The peak is absent in axially symmetric or spherical nuclei, serving as a tetrahedral shape indicator.

The method links excitation mode features to nuclear shape deformation.

Abstract

The multipole modes of excitation for tetrahedrally deformed neutron-rich Zr isotopes are investigated using the quasiparticle finite amplitude method based on the covariant density functional theories. By employing the density-dependent point-coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel and a separable pairing interaction of finite range, it is observed that a distinct peak emerges at $\omega = 9.0 - 10.0$ MeV in the isoscalar quadrupole $K=0$ strength when $\beta_{32}$ distortion is considered for $^{110,112}$Zr. This peak is absent when the deformation is limited to axially symmetric octuple or spherical case. It also does not appears in neighboring axially quadrople or octupole deformed nuclei, thus can be viewed as an indicator for the tetrahedral shape.