Using Woods-Saxon potentials and the eigenphase formalism for one-particle resonances, one-particle bound and resonant levels for neutrons as a function of quadrupole deformation are presented, which are supposed to be useful for the interpretation of spectroscopic properties of some light neutron-rich nuclei with weakly-bound neutrons. Compared with Nilsson diagrams in text books which are constructed using modified oscillator potentials, we point out a systematic change of the shell structure in connection with both weakly-bound and resonant one-particle levels related to small orbital angular momenta $\ell$. Then, it is seen that weakly-bound neutrons in nuclei such as $^{ 15-19}$C and $^{ 33-37}$Mg may prefer to being deformed as a result of Jahn-Teller effect, due to the near degeneracy of the 1d$_{ 5/2}$-2s$_{ 1/2}$ levels and the 1f$_{ 7/2}$-2p$_{ 3/2}$ levels in the spherical potential, respectively. Furthermore, the absence of some one-particle resonant levels compared with the Nilsson diagrams in text books is illustrated.
Categories: nucl-th
