COLLECTIVE MODES OF EXCITATION IN DEFORMED NEUTRON-RICH Mg ISOTOPES

Abstract

Giant resonances and the pygmy mode in neutron-rich Mg isotopes close to the drip line are investigated by means of the deformed Hartree-Fock-Bogoliubov and quasiparticle random-phase approximations using a Skyrme energy-density functional. It is found that the giant monopole resonance has a two-peak structure due to the deformation. The lower-energy resonance is generated associated with the mixing with the Kπ = 0+ component of the giant quadrupole resonance. We find for the negative-parity excitations that the pygmy dipole resonance appeared just above the threshold has a significant mixing effect among the isovector dipole, isoscalar octupole and compression dipole excitations.