类碳和类硅高电荷离子精细结构的电场效应研究

The carbon-like and silicon-like highly charged ions(HCIs) with two p valance-shell electrons, are the ideal ions, which use magnetic-dipole transition of the same fine-structure manifolds as a basis of an optical clockwork. High-precision calculations of effects of the external electric field on the magnetic-dipole transition, such as the electric quadrupole shift, AC/DC Stark shift, and black-body radiation shift, play an important role in the implementation of highly charged ion optical clock scheme. In this project, we will combine configuration interaction and Dirac-Fock plus core polarization method to study the external electric field effects of the carbon-like ions with Z=17-23, and the silicon-like ions with Z=26-32. The quadrupole moment for the 3P1 state, and the static or dynamic polarizabilities for 3P0 and 3P1 states are calculated with high accuracy. In addition, the electric quadrupole shift, AC/DC Stark shift, and black-body radiation shift for the magnetic dipole transition of 3P0-3P1 between the fine structure levels of the ground state are determined quantitatively. The precise calculations of the electric quadrupole moment, static and dynamic polarizabilities will resolve the shortage of theoretical data for those HCIs. Meanwhile, the accurate and quantitative evaluations of the electric effects on the magnetic-dipole transition, will provide important and reliable theoretical inputs to the design of HCI optical clock project, especially for the systematic uncertainties evaluations.

两个p价电子的类碳和类硅高电荷离子(HCIs)是以电子基态的同一套精细结构简并态间的光频磁偶极跃迁为钟跃迁的理想体系。 精确计算外加电场引起的磁偶极跃迁频移，包括电四极矩频移、AC/DC斯塔克频移和黑体辐射频移，对HCI光钟实验具有重要意义。本项目拟利用相对论组态相互作用(RCI)结合芯极化势(DFCP)的方法，理论研究核电荷数Z=17-23的类碳和核电荷数Z=26-32的类硅HCIs的外电场效应。高精度计算类碳和类硅高电荷离子体系3P1态的电四极矩，以及3P0和3P1态的静电/动力学极化率；精确定出类碳和类硅高电荷离子体系基态精细结构能级3P0-3P1磁偶极跃迁的电四极矩频移、AC/DC斯塔克频移及黑体辐射频移。本项目中电四极矩、静电/动力学极化率的精确计算将解决HCIs相关理论数据零散不全或精度低的问题，同时外电场效应的精确计算，也可为新型光钟的设计和系统误差的分析提供重要的理论支持。

高电荷离子精细结构与超精细结构的原子性质与外场效应的理论研究对于新型光钟候选体系的遴选以及实验上新型光钟的构建有重要意义。本项目采用相对论组态相互作用(RCI)结合Dirac-Hartree-Fock的方法，研究了类硅高电荷离子Ni14+，及其相邻电荷态的Ni11+ 、Ni12+和Ni15+离子电子基组态的精细与超精细能级结构，重点分析了电子关联效应、Breit相互作用和量子电动力学效应的影响，高精度获得了磁偶极和电四极跃迁的跃迁波长、上态寿命和品质因子等，初步遴选出六个适合研制光钟的跃迁；进一步计算了相关跃迁态的电四极矩，分析了消除电四极矩频移的方法，推荐采用61Ni元素发展高电荷镍离子光钟，以达到减小或消除钟跃迁电四极矩频移的目的；同时研究了跃迁频率对精细结构常数变化的敏感程度，发现类硅Ni14+离子的磁偶极和电四极跃迁对精细结构常数变化的敏感度优于现有的实验室光钟体系（除Hg+和Yb+以外）,并且由于Ni12+的E2跃迁比Yb+的E2跃迁具有更大的K值和更小的系统与统计误差，通过比较基于Ni12+的E2跃迁和Yb+的E3跃迁的两个时钟，有望进一步推进探索精细结构常数随时间变化的研究。本项目的理论计算对实验上高电荷离子钟方案的实施提供理论数据支持，与实验密切结合在一定程度上有望推进高电荷镍离子钟的实现。

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