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
β. Then, it is seen that weakly-bound neutrons in nuclei such as
15β19C and 33β37Mg may prefer to being deformed as a result of
Jahn-Teller effect, due to the near degeneracy of the 1d5/2β-2s1/2β
levels and the 1f7/2β-2p3/2β 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.Comment: 12 pages, 5 figure