Eur. Phys. J. A (2009) 42: 583-590
https://doi.org/10.1140/epja/i2008-10742-y

Regular Article - Theoretical Physics

Skyrme-QRPA calculations for low-lying excitation modes in deformed neutron-rich nuclei

Nishina Center for Accelerator-Based Science, RIKEN, 351-0198, Wako, Saitama, Japan

^* e-mail: Kenichi.Yoshida@riken.jp

Received: 8 December 2008
Revised: 13 January 2009
Accepted: 6 February 2009
Published online: 17 March 2009

Abstract

Low-frequency modes of excitation in deformed neutron-rich nuclei are studied by means of the quasiparticle random-phase approximation on the Skyrme-Hartree-Fock-Bogoliubov mean field. We investigate the microscopic structure of the soft modes systematically in neutron-rich magnesium isotopes with N = 22, 24, 26 and 28 close to the drip line, and it is found that the strong collectivity in ³⁴Mg and ⁴⁰Mg is acquired due to the coherent coupling between the vibration and the pairing vibration of neutrons. Microscopic structure of the modes changes gradually associated with the location of the Fermi level of neutrons, and it is found that the proton particle-hole excitation generating the -vibrational mode in ²⁴Mg continues to play a key role in the near-drip-line nucleus ⁴⁰Mg . The low-frequency octupole excitations are also investigated and the microscopic mechanism for the enhancement of transition strengths is discussed.