Eur. Phys. J. A 13, 43-47 (2002)
Molecular-orbital structure in neutron-rich Be and C isotopesN. Itagaki1, S. Okabe2, K. Ikeda3 and I. Tanihata3
1 Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
2 Center for Information and Multimedia Studies, Hokkaido University, Japan
3 RIB Science Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
(Received: 1 May 2001)
The structure of Be and C isotopes are investigated based on the molecular-orbit (MO) model. The low-lying states are characterized by several configurations of valence neutrons, which are constructed as combinations of basic orbits. In 10Be, all of the observed positive-parity bands and the negative-parity bands are described within the model. The second 0+ state of 10Be has a large - cluster structure, and this is characterized by a configuration. An enlargement of the - distance due to two-valence neutrons along the - axis makes their wave function smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling between the Sz=0 and the Sz=1 configurations, is important. In the ground state of 12Be, the calculated energy exhibits similar characteristics, that the remarkable clustering and the contribution of the spin-orbit interaction make the binding of the state with configuration properly stronger in comparison with the closed p-shell configuration. This is related to the breaking of the N=8 (closed p-shell) neutron magic number. Also, the molecule-like structure of the C isotopes is investigated using a microscopic + + + n+ n+ model. The combination of the valence neutrons in the - and the -orbit is promising to stabilize the linear-chain state against the breathing and bending modes, and it is found that the excited states of 16C are the most promising candidates for such structure.
21.10.-k - Properties of nuclei; nuclear energy levels.
21.60.Gx - Cluster models.
© Società Italiana di Fisica, Springer-Verlag 2002