Searching for 4$\alpha$ linear-chain structure in excited states of $^{16}$O with a covariant density functional theory
Searching for 4$\alpha$ linear-chain structure in excited states of $^{16}$O with a covariant density functional theory
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DOI：
10.1103/physrevc.90.054307
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发表时间：
2014-03
影响因子：
3.1
通讯作者：
J. Yao;N. Itagaki;J. Meng
中科院分区：
文献类型：
--
作者：
J. Yao;N. Itagaki;J. Meng
用协变密度泛函理论研究了$^{16}$O高激发态的4 α线性链结构.利用生成坐标法（GCM）对粒子数和角动量投影的四极形变平均场态进行组态混合，得到了低自旋态。高自旋态是由推转计算确定的。这两个计算基于相同的能量密度泛函PC-PK 1。我们已经发现了LCS候选人在高躺低自旋GCM状态和曲柄高自旋状态具有相似的转动惯量和带头能量，估计分别为0.11 MeV和30 MeV左右。内禀组态被认为是4 $\alpha $团簇沿着一个公共轴，核子以非定域方式占据$（s）^4（p）^4（d）^4（f）^4$组态的组态。结果表明，在LCS态中，所有核子的自旋和轨道角动量是平行的，但自旋轨道分裂能之和远小于类壳态的自旋轨道分裂能之和.此外，我们的全微观GCM计算很好地再现了第二个$0^+$态的转动带的激发能和$B（E2）$值，该态具有$^{12}$C+$\alpha$结构，其主要构型是四个“风筝”状的$\alpha$团簇.
A study of 4$\alpha$ linear-chain structure (LCS) in high-lying collective excitation states of $^{16}$O with a covariant density functional theory is presented. The low-spin states are obtained by configuration mixing of particle-number and angular-momentum projected quadrupole deformed mean-field states with generator coordinate method (GCM). The high-spin states are determined by cranking calculations. These two calculations are based on the same energy density functional PC-PK1. We have found the LCS candidate in both high-lying low-spin GCM states and cranking high-spin states with similar moment of inertia and band-head energy, which are estimated to be around 0.11 MeV and 30 MeV, respectively. The intrinsic configuration is considered to be the one that 4$\alpha$ clusters stay along a common axis and nucleons occupy the $(s)^4(p)^4(d)^4(f)^4$ configurations in a nonlocal way. Moreover, our results indicate that the spin and orbital angular momenta of all nucleons are parallel in the LCS states but the sum of spin-orbit splitting energies turns out to be much smaller than that of shell-like state. Besides, our fully microscopic GCM calculation has reproduced the excitation energies and $B(E2)$ values rather well for the rotational band built on the second $0^+$ state which has been previously considered to have $^{12}$C+$\alpha$ structure, and the dominant configuration turns out to be four $\alpha$ clusters with "kite"-like shape.