当前原子核物理中最重要的课题之一是第一性原理计算，即基于真实的核子-核子相互作用研究原子核的结构与反应。本项目将真实核力通过幺正关联算符方法(UCOM）变换后应用到蒙特卡罗壳模型(MCSM)计算中，系统地研究轻原子核的低激发谱。首先，通过引入一个包含中心和张量关联算符的幺正算符，把包含真实核力的体系哈密顿量变换成一个有效的哈密顿量。其次，通过蒙特卡罗模拟，筛选出权重较大的基矢波函数，从而大大降低空间维度。最后，利用这些基矢波函数把有效哈密顿量对角化，得到体系的本征值和本征波函数。本项目将系统地研究轻原子核低激发态的结合能、四极矩、电磁跃迁强度、g因子和单粒子能级占据几率等，从而获取轻核低激发态各种性质的微观机制，解释实验现象并给出理论预言，同时探索第一性原理计算当前所能达到的核素极限。此外，项目还将尝试理解核力中一些重要成分，例如张量力对于模型空间的依赖性，以及它对轻原子核性质的影响。

One of the major goals in nuclear physics is to understand the structure and reactions of nuclei starting from realistic nuclear interactions。 That is so-called ab initio calculations. In this project, the low-lying spectra of light nuclei is investigated systematically in the framework of Monte Carlo Shell Model (MCSM) by using the realistic nuclear force transformed by UCOM.This transformation is operated by a unitary operator, which includes a central correlation operator and a tensor correlation operator. In the meantime, the dominant basis wave functions can be selected by Monte Carlo sampling in order to reduce the dimension of the Hamiltonian matrix. The eigenvalues and eigenvectors of the nuclear many-body system then can be evaluated by the diagonalization. In this project, the binding energy,quadrupole moment, electromagnetic transitions, g-factor and the single particle orbit occupation probability of low-lying strectra for light nuclei will be investigated systematically in order to obtain the microscopic mechanism inside.The MCSM calculation results can be used to explain or predict the experimental phenomena. A perspective for the limitation of present ab inition calculation is also expected in this project. Moreover, we try to understand the contribution of some important parts of nuclear force, such as tensor force, to the properties for light nuclei.