基于壳模型配对近似的形变原子核结构微观研究

原子核形变、集体运动、形状演化和相变是原子核物理的重要课题之一。与Nilsson平均场模型、几何集体模型等形变理论的出发点不同，壳模型基于组态相互作用方法研究轻核区和中等质量区形变原子核。在重质量区，Sm、Gd等同位素链表现出比较明显的形状相变现象，闯入轨道对原子核的集体性发挥重要作用，但是大规模壳模型的组态空间维数太大难以处理。因此在壳模型框架下对重质量区形变原子核的研究是人们长期关注的难题之一。本项目拟发展大规模壳模型的配对近似理论m-scheme计算方法，在此基础上开展与形变原子核相关的核结构理论研究工作，主要包括形变原子核的配对近似组态、稀土区原子核从球形到四极形变的演化和相变、八极形变原子核的低激发态性质和Schiff矩。本项目的研究成果将为原子核集体运动和结构演化提供进一步的理论解释，加深对原子核配对机制的理解，为强相互作用CP对称性破缺的研究提供理论支持。

The nuclear deformations, collective motions, shape evolution and phase transition have always been one of the most important frontiers in nuclear physics. Deformed nuclei are usually studied in nuclear structure theories such as the Nilsson mean-field model and the geometric collective model, where the permanent deformations are emphasized. From another perspective, deformed nuclei in the light- and medium-mass regions have also been studied based on the configuration interaction method in the shell model. In the heavy-mass region, the Sm and Gd isotopes exhibit obvious phenomena of the shape phase transition, and the intruded single-particle orbits play an important role in nuclear collectivities, however, the configuration space of the large-scale shell model is too gigantic to handle. Handling well-deformed heavy-mass nuclei in the frame work of the shell model has been a long standing problem. In this proposal, we shall develop a large-scale m-scheme algorithm for the nucleon-pair approximation of the shell model and study several issues associated with deformed nuclei. Our study includes nucleon-pair configurations for deformed nuclei, nuclear shape evolution and phase transition from the spherical shape to the quadrupole deformation in the rare-earth region, low-lying states of octupole-deformed nuclei and the nuclear Schiff moment. The accomplishment of this project shall provide a deeper understanding of nuclear collective motions, structure evolutions, nucleon-pair correlations, and the strong CP violation.