基于能量密度泛函理论研究对关联对原子核裂变过程的影响

Investigation of the Impact of Pairing Correlations on the Nuclear Fission Process Based on the Energy Density Functional Theory

以^(239)Pu的中子诱发裂变为例,系统研究了对力形式的不确定性以及对关联强度的不确定性对裂变可观测量的影响,从而揭示了对关联在裂变过程所起的作用。首先使用基于Skyrme有效核力的能量密度泛函理论(DFT)计算了^(240)Pu二维形变空间中的静态裂变位能曲面,在Hartree-Fock-Bogoliubov (HFB)近似中分别使用了体积型、表面型及混合型对力,并测试了不同对力强度的影响;然后基于密度泛函的计算结果,进一步采用含时生成坐标(TDGCM)和高斯重叠近似(GOA)方法开展了^(240)Pu裂变动力学计算。通过分析讨论了对力类型和对力强度变化对裂变过程中相关物理量的影响,发现对力强度的改变在原子核小形变、大形变区域均有明显影响,然而对力类型的改变主要在大形变区域会产生明显差异。原子核的大形变组态会对裂变动力学过程产生比较重要的影响。计算结果表明,不同的对力类型得到的大形变组态会有较为显著的差别,因而合适的对力类型的选取对裂变描述是比较重要的,混合对力在裂变计算中效果最佳。

This study systematically investigates the impacts of uncertainties in the form and the strength of the pairing force on observables related to nuclear fission,taking the neutron-induced fission of ^(239)Pu as an example,thereby revealing the role of pairing in the fission process.The energy density functional theory(DFT)based on the Skyrme force was employed to calculate the potential energy surface in the two-dimensional deformation space of ^(240)Pu,using volume,surface,and mixed pairing forces within the Hartree-Fock-Bogoliubov(HFB)approximation.And we also test the effects of varying pairing strengths for the mixed pairing force.Subsequently,based on the DFT calculations,the fission dynamics of 240Pu were further studied using the Time-Dependent Generator Coordinate Method(TDGCM)plus the Gaussian Overlap Approximation(GOA).By analyzing the influence of varying the types or the strength of the pairing force on fission related properties,we found that variation in the pairing strength significantly affect both small and large deformation regions.However,alterations in pairing force type primarily cause notable differences in the large deformation region.The configurations at large deformation in the nucleus have significant impacts on the fission dynamics.Our results show that there are explicit differences in the configurations at large deformations obtained by different types of pairing force,so the choice of pairing force is very important for the fission description.The mixed-type of pairing force gives the best results in the calculation of fission dynamics.