N = Z = 40 附近核集体性的从头计算涌现与坍缩
Ab Initio Emergence and Collapse of Nuclear Collectivity near N = Z = 40
- School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）
- Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing, Sun Yat-sen University（中山大学广东省量子计量与传感重点实验室）
- School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University（北京大学物理学院及核物理与核技术国家重点实验室）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文通过从头计算揭示 N=Z=40 附近原子核四极集体性的涌现与坍缩，发现其由 1g9/2–2d5/2 间距变化主导，无需经验有效电荷即可描述 80Zr 的强形变及其向邻近核的减弱。
AI中文摘要：
我们利用手征二体和三体力通过介质相似性重正化群导出的多壳价空间哈密顿量，对 N = Z = 40 附近原子核中增强的四极集体性的涌现与坍缩进行了从头计算描述。采用一致演化的 E2 算符的投影生成坐标计算，无需经验有效电荷即可捕捉到 ⁸⁰Zr 中的强集体性及其向 ⁸⁶Mo 和 ⁸⁸Ru 的减弱。虽然 N, Z = 40 的有效单粒子能隙保持开放，但 1g₉/₂–2d₅/₂ 间距在 ⁷⁶Sr 和 ⁸⁰Zr 附近最小，其变化主要由质子-中子单极贡献主导。相关的占据数与涉及赝 SU(3) pf 空穴和准 SU(3) 粒子的四极关联一致。将质子和中子 2d₅/₂ 的占据排除在变分空间之外会强烈抑制 ⁸⁰Zr 中的形变和 B(E2;2₁⁺→0₁⁺)。这些结果标志着向重开壳核从头计算迈出了坚实的一步。
英文摘要：
We present an \textit{ab initio} description of the emergence and collapse of enhanced quadrupole collectivity in nuclei near $N=Z=40$ using multi-shell valence-space Hamiltonians derived from chiral two- and three-nucleon forces with the in-medium similarity renormalization group. Projected generator-coordinate calculations with consistently evolved $E2$ operators capture the strong collectivity in $^{80}$Zr and its decrease toward $^{86}$Mo and $^{88}$Ru without empirical effective charges. While the $N,Z=40$ effective single-particle energy gaps remain open, the $1g_{9/2}$--$2d_{5/2}$ spacing is smallest near $^{76}$Sr and $^{80}$Zr, with its variation governed mainly by the proton-neutron monopole contribution. The associated occupancies are consistent with quadrupole correlations involving pseudo-SU(3) $pf$ holes and quasi-SU(3) particles. Excluding the occupation of the proton and neutron $2d_{5/2}$ from the variational space strongly suppresses the deformation and $B(E2;2_1^+\rightarrow0_1^+)$ in $^{80}$Zr. These results mark a steady step toward \textit{ab initio} computations of heavy open-shell nuclei.
