论文标题
壳模型的核子对中等重核的截断
Nucleon-pair truncation of the shell model for medium-heavy nuclei
论文作者
论文摘要
背景：原子核的计算可及其模型是核结构物理学的长期目标。一个容易包含激发态和多体相关性的灵活框架是配置相互作用的壳模型（SM），但是基础的指数增长意味着一个人需要有效的截断方案，理想情况下是一种既有变形和配对相关性。 目的：我们提出了SM：从Hartree-fock单粒子状态定义的对凝结物变化和粒子空的保守的Bardeen-Cooper-Schrieffer（NBCS）近似的有效截断方案，我们对状态进行良好的角动力进行投影。 方法：在SM空间中生成具有KRAMERS变性的Hartree-Fock单粒子状态后，我们通过最小化能量，然后使用具有良好角度动量的状态的线性代数投影（LAP）来优化NBC中的对振幅。 NBC和LAP在计算上都很快。 结果：我们的计算与中等和重型区域的轴向对称和三轴变形的低较低和旋转核的低洼状态具有完整的配置交流SM计算：$^{44,46,48} $^{446,48} $ ti，$^ $^{66,68} $ ge，$^{68} $ se和$^{108,110} $ xe。我们预测$^{112-114} \ textrm {ba} $和$^{116-120} \ textrm {ce} $的低洼状态，通过大规模SM计算很难达到核。 结论：配对相关性和不同固有状态之间的构型混合在复制集体和形状共存方面都起着关键作用，这证明了SM的这种截断方案在研究过渡性和变形核中的实用性。
Background: Computationally tractable models of atomic nuclei is a long-time goal of nuclear structure physics. A flexible framework which easily includes excited states and many-body correlations is the configuration-interaction shell model (SM), but the exponential growth of the basis means one needs an efficient truncation scheme, ideally one that includes both deformation and pairing correlations. Purpose: We propose an efficient truncation scheme of the SM: starting from a pair condensate variationally defined by Hartree-Fock single-particle states and the particle-number conserved Bardeen-Cooper-Schrieffer (NBCS) approximation, we carry out projection of states with good angular momentum. Methods: After generating Hartree-Fock single-particle states with Kramers degeneracy in a SM space, we optimize the pair amplitudes in the NBCS by minimizing the energy, and then use linear algebra projection (LAP) of states with good angular momentum. Both NBCS and LAP are computationally fast. Results: Our calculations yield good agreement with full configuration-interaction SM calculations for low-lying states of transitional and rotational nuclei with axially symmetric and triaxial deformation in medium- and heavy-mass regions: $^{44,46,48}$Ti, $^{48,50}$Cr, $^{52}$Fe, $^{60,62,64}$Zn, $^{66,68}$Ge, $^{68}$Se, and $^{108,110}$Xe. We predict low-lying states of $^{112-114}\textrm{Ba}$ and $^{116-120}\textrm{Ce}$, nuclei difficult to reach by large-scale SM calculations. Conclusions: Both pair correlation and the configuration mixing between different intrinsic states play a key role in reproducing collectivity and shape coexistence, demonstrating the utility of this truncation scheme of the SM to study transitional and deformed nuclei.
