现代壳模型

Contemporary Nuclear Shell Models

传统壳模型存在的一个主要问题是计算过于复杂以致无法进行.随着计算机计算能力的空前提高,现在已经可以进行极大规模的壳模型计算.然而,还不清楚这种计算对于深入理解物理问题是否有实际帮助.况且,对于组态空间可达1014—1018维的中重核,当前的计算机能力还达不到.因此对中重核仍需研究如何把巨大的模型空间截断到最佳的可操作子空间的问题.近来提出的配对壳模型给出了一个很有用的方法,其它截断模型可归入它的特殊情况.与此同时,从现实有效二体相互作用出发进行壳模型多体计算方面也正在取得巨大的进展.

The current status on the theoretical investigations of the nuclear shell model is reviewed, and the fundamental problems in shellmodel studies are mentioned. Basically the shellmodel uses a very intuitive approach to study the nuclear manybody dynamics in terms of valence particles. It assumes that the nucleons, belonging to a closed core, do not participate in the establishment of the nuclear spectrum. One of the main problems in the (traditional) shell model is to make a calculation feasible. With the explosive growth of the computational power, it is possible to carry out a 'Very Large Scale' shell model calculation. Nevertheless, whether such a calculation really helps our understanding of physics is still an open question. Furthermore, the case of the medium weight and heavy nuclei with configurations of 1014-1018 remains out of reach. For these nuclei one still needs to truncate the huge shell model space to a manageable subspace. Recently, a useful formalism has been described for the nuclearpair shell model, which allows for various truncations. Meanwhile, nuclear manybody shell model calculations with realistic effective interactions have been undergoing developments tremendously.