Core polarization for the electric quadrupole moment of neutron-rich aluminum isotopes

The core polarization effects for the electric quadrupole moments of the neutron-rich 31Al, 33Al, and 35Al isotopes in the vicinity of the island of inversion are investigated by means of the microscopic particle-vibration coupling model in which the Skyrme Hartee-Fock-Bogoliubov and quasiparticle random-phase approximations are used to calculate the single-quasiparticle wave functions and the excitation modes. It is found that the polarization charge for the proton 1d5/2 hole state in 33Al is quite sensitive to coupling to the neutrons in the pf-shell associated with the pairing correlations and that the polarization charge in 35Al becomes larger due to the stronger collectivity of the low-lying quadrupole vibrational mode in the neighboring 36Si nucleus.