Molecular orbital structures in 10 Be
Molecular orbital structures in 10 Be
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10 Be 的分子轨道结构
DOI：
10.1103/physrevc.61.044306
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发表时间：
2000
影响因子：
3.1
通讯作者：
S. Okabe
中科院分区：
文献类型：
--
作者：
N. Itagaki;S. Okabe
采用基于分子轨道（MO）模型的微观$\ensuremath{\alpha}+\ensuremath{\alpha}+n+n$模型研究了${}^{10}\ mathm {Be}$的结构。低洼态的特点是价中子的几种构型，它们被构造为三个基本轨道的组合。所采用的模型空间在传统MO模型的基础上进行了扩展，将轨道表示为局部高斯函数的线性组合。他们的立场是不同的。利用该模型，我们重新分析了${}^{9}\ mathm {Be}$的结构，并表明该扩展使我们能够使用由$\ensuremath{\alpha}\ensuremath{-}n的散射相移分析确定的原始两体自旋轨道相互作用。在${}^{10}\mathrm{Be}中，在模型中描述了所有观测到的正奇偶校验带和负奇偶校验带。${0} ^{+} $基态的$ {}^ {10}\ mathrm{是}$所描述的是一个占主导地位的$ {(3/2}^ {\ ensuremath{-}}{)} ^{2} $配置。该态具有相当大的结合能（实验值为$\ensuremath{\alpha}+\ensuremath{\alpha}+n+n$阈值为8.38 MeV），并详细讨论了导致结合的机制，如配对效应和两个团簇之间动能的降低。尽管有这么大的结合，基态中的$\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$聚簇仍然存在，这是由于${}^{6}\ mathm {He}+\ensuremath{\alpha}$配置和${}}^{5}\ mathm {He}{+}^{5}\ mathm {He}$配置之间的耦合效应，这为价中子提供了一个光滑的势。${}^{10}\ mathm {Be}$的第二个${0}^{+}$状态有一个大的$\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$结构和${(1/2}^{+}{)}^{2}$配置。由于双价中子沿$\ensuremath{\alpha}\ensuremath{\alpha}}轴的距离增大，使它们的波函数平滑，并大大降低了动能。此外，由于${S}_{z}=0$和${S}_{z}=1$构型之间的耦合，自旋轨道相互作用的贡献是重要的。我们还展示了两个价中子在两个$\ensuremath{\alpha}$团簇之间的中介作用。
The structure of ${}^{10}\mathrm{Be}$ is investigated using a microscopic $\ensuremath{\alpha}+\ensuremath{\alpha}+n+n$ model based on the molecular orbit (MO) model. The low-lying states are characterized by several configurations of valence neutrons, which are constructed as combinations of three basic orbits. The model space employed is extended from the traditional MO models, and the orbits are expressed as linear combinations of local Gaussians. Their positions are determined variationally. Using this model, we reanalyze the structure of ${}^{9}\mathrm{Be}$ and show that this extension enables us to use the original two-body spin-orbit interaction determined from a scattering phase-shift analysis of $\ensuremath{\alpha}\ensuremath{-}n.$ In ${}^{10}\mathrm{Be},$ all of the observed positive-parity bands and the negative-parity bands are described within the model. The ${0}^{+}$ ground state of ${}^{10}\mathrm{Be}$ is described by a dominant ${(3/2}^{\ensuremath{-}}{)}^{2}$ configuration. The state has a rather large binding energy (8.38 MeV from the $\ensuremath{\alpha}+\ensuremath{\alpha}+n+n$ threshold experimentally), and the mechanism leading to binding, such as a pairing effect and reduction of the kinetic energy between two clusters, is discussed in detail. In spite of this large binding, the $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ clustering in the ground state persists due to a coupling effect between the ${}^{6}\mathrm{He}+\ensuremath{\alpha}$ configuration and the ${}^{5}\mathrm{He}{+}^{5}\mathrm{He}$ configuration, which provides a smooth potential for the valence neutrons. The second ${0}^{+}$ state of ${}^{10}\mathrm{Be}$ has a large $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ structure with a ${(1/2}^{+}{)}^{2}$ configuration. An enlargement of the $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ distance due to two-valence neutrons along the $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ axis makes their wave function smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling between the ${S}_{z}=0$ and the ${S}_{z}=1$ configurations is important. We also show the mediation effect of two valence neutrons between two $\ensuremath{\alpha}$ clusters.