适用于配对近似计算的集体对凝聚组态变分方法

集体对凝聚组态(collective-pair condensate)的能量变分可用于判断在原子核低激发态中哪些集体对是重要的，并且可以同时给出这些重要集体对的具体结构。这在一定程度上缓解了此前原子核配对近似(Nucleon Pair Approximation, NPA)计算一直深受困扰的集体对不确定性问题。针对过渡区原子核132Ba的试探性计算体现了这种方法的优越性。它可以给出132Ba的三轴形变参数，它也定量地说明了这一原子核$I\!=\!10$基带回弯效应的主导集体对种类。更为重要的是，中子负宇称对凝聚状态的变分计算解释了为什么负宇称集体对这种回弯效应可以呈现出巨大影响。

Variational Approach for Pair Determination in Nucleon Pair Approximation

We propose a pair-condensation variation approach to evaluate the importance of collective pairs and determine their structure in low-lying states. Based on such a variation, the Nucleon Pair Approximation(NPA) could avoid the collective-pair uncertainty, which the previous NPA calculations have suffered a lot. With the trial calculation for transitional 132Ba, we exemplify the ability of our variation approach. In detail, the variation can be adopted to calculate the quadrupole deformation parameters with non-axisymmetric deformation degree of freedom. It conclusively helps the NPA to decide which collective pair is essential for obtaining a lower yrast level scheme and reproducing the $I\!=\!10$ backbending. With the optimized condensation of neutron negative-parity pairs, we explain why the neutron negative-parity pairs have a large impact on the backbending behavior.