Coexistence phenomena of chemical-bonding-like structures in neutron excess systems

广义双中心团簇模型可以处理一般双中心系统中的共价组态和原子组态，并应用于轻中子系12BE=.+。+4N。研究了激发态能级的本征结构。我们发现，在非结合区，+8He和5He+7He的离子结构以及6He+6He的原子结构都是产生的，尽管在结合区以共价结构为主。在同一能区还实现了具有共价结构和He-二聚体结构的混合构型的奇异超形变。这些非束缚态的能级方案显示出一种强烈的简并特征，具有相当大的不同组态的混合。目前的结果有力地表明，这种简并特征可以推广到较轻质量区的一般中子过剩系统。

The generalized two-center cluster model (GTCM), which can treat covalent and atomic configurations in general two center systems, is applied to the light neutron-excess system, 12Be = . + . + 4N. The intrinsic structure of the excited energy levels is investigated. We found that, in an unbound region, the ionic structures of .+8He and 5He+7He, the atomic structure of 6He+6He are generated although the covalent structures are dominant in the bound region. An exotic superdeformation, which has a hybrid configuration of both the covalent and He-dimer structures, is also realized in the same energy region. The level scheme of these unbound states reveals a strong degenerate feature with a considerable mixture of the different configurations. The present result strongly suggests that such a degenerate feature can be generalized to general neutron-excess systems in the lighter mass region.