Using the singles and doubles approximated relativistic coupled-cluster method, we calculate hyperfine-structure constant A and B of 24 low-lying states of La²⁺. The results of the lowest four states 5d _3/2,5/2 and 4f _5/2,7/2 are compared with recently measured values (Olmschenk etal 2017 Phys. Rev. A 96 032502). Reasonable agreement is found for hyperfine-structure constant A of 5d _3/2 and 4f _5/2,7/2 states, but the hyperfine-structure constant A of 5d _5/2 and the hyperfine-structure constant B have a large deviation. To understand the role of the electron correlation effect, the intermediate results from lower-order many-body perturbation-theory and the linear version of coupled-cluster with single and double approximation are also presented. In the framework of coupled-cluster theory, the contribution trends from individual correlation effects are also investigated.

使用单双打近似相对论耦合簇方法，我们计算超精细结构常数甲和乙的镧24低洼状态²⁺。将最低的四个状态 5 d _3/2,5/2和 4 f _{5/2,7/2 的}结果与最近的测量值进行比较（Olmschenk等人2017 Phys. Rev. A 96 032502）。合理的协议被发现为超精细结构常数阿5的d _3/2和4 ˚F _{5 / 2,7 / 2}的状态，但超精细结构常数阿5的d _5/2和超精细结构常数B有很大的偏差。为了理解电子相关效应的作用，还介绍了低阶多体微扰理论的中间结果和线性版本的单近似和双近似耦合簇。在耦合聚类理论的框架内，还研究了个体相关效应的贡献趋势。