Mixed representation RPA calculation for octupole excitations on superdeformed states in the 40Ca and neutron-rich sulfur regions

By means of the mixed representation RPA based on the Skyrme–Hartree–Fock mean field, we investigate low-frequency octupole excitations built on the superdeformed (SD) states in the N=Z nuclei around 40Ca and the neutron-rich sulfur isotopes. The RPA calculation is carried out fully self-consistently on the three-dimensional Cartesian mesh in a box, and yields a number of low-frequency octupole vibrations built on the SD states in 32S, 36Ar, 40Ca and 44Ti. In particular, a strongly collective Kπ=1− octupole vibration is suggested to appear on top of the SD state in 40Ca. For 48,50S close to the neutron drip line, we find that the low-lying state created by the excitation of a single neutron from a loosely bound low Ω level to a high Ω resonance level acquires an extremely strong octupole transition strength due to the spatially very extended structure of the particle–hole wave functions.