Low-lying excitation modes in deformed neutron-rich nuclei

Low-frequency modes of excitation in deformed neutron-rich nuclei are studied by the use of the deformed quasiparticle-random-phase approximation (QRPA) based on the coordinate-space Hartree–Fock–Bogoliubov formalism. We investigate the microscopic structure of the low-lying K^π = 0⁺ modes in neutron-rich Mg, Cr and Fe isotopes. It is found that the spatially extended structure of neutron quasiparticle wave functions around the Fermi level brings about a striking enhancement of the transition strengths. It is also found that the fluctuation of the pairing field plays an important role in generating coherence among two-quasiparticle excitations of neutron. Recent progress towards the self-consistent deformed QRPA calculation using the Skyrme density functional is also presented. (author)