物理学报2017，Vol.66Issue(11)：71-77,7.DOI:10.7498/aps.66.113101
采用相对论多组态Dirac-Hartree-Fock方法对Mg原子同位素位移的理论研究
Theoretical calculations on isotope shifts of Mg I by using relativistic multiconfiguration Dirac-Hartree-Fock method
摘要
Abstract
The isotope shift parameters for the atomic transitions 1S0-1p1 and 1S0-3p1 of Mg are calculated by the relativistic multiconfiguration Dirac-Hartree-Fock (MCDHF) method,including the normal mass shift (NMS) coefficients,the specific mass shift (SMS) coefficients and the field shift (FS) factors.The detailed calculations of the isotope shifts for the three stable isotopes 24Mg,25Mg and 26Mg are also carried out,in which the GRASP2K package is used together with another modified relativistic isotope shift computation code package RIS3.The two-parameter Fermi model is used here to describe the nuclear charge distribution in order to calculate the field shift by the first-order perturbation.A restricted double excitation mode is used in our calculations,one electron is excited from the two electrons in the 3s shell (3s2),another electron is excited from the eight electrons in the 2s or 2p shells (2s22p6),and the two electrons in the 1s shell (1s2) are not excited.The active configurations are expanded from the occupied orbitals to some active sets layer by layer,and each correlation layer is numbered by the principal quantum numbers n (n =3,4,5,...) and contains the corresponding orbitals s,p,d,....The active configurations with the mixing coefficients in the added layer can be optimized by the MCDHF calculations.In this work,the atomic state functions are optimized simultaneously by the self-consistent field method and the relativistic configuration interaction approach in which the Breit interaction is taken into account perturbatively as well.The maximum principal quantum number n equals 10 and the largest orbital quantum numberlmax is g.In our calculations,the NMS coefficients are-576.8 and-359.9 GHz.u,the SMS coefficients are 133.9 and-479.6 GHz.u,and the FS factors are-62.7 and-78.0 MHz.fm-2 for the 1S0-1p1 and 1S0-3p1 transitions of Mg,respectively.The difference between our isotope shift calculations and the previous experimental measurements is in a range from 6 MHz to 20 MHz with the relative error range from 0.6％ to 1.3％,which shows that our results are in good agreement with experimental values.Our calculations are also coincident with other theoretical results.The isotope shift parameters provided here can be applied to the quick calculations of isotope shifts for the short-lived Mg isotopes,including 20-23Mg and 27-40Mg,and can be referred to for the corresponding isotope shift experiments.The methods used here can be applied to calculating the isotope shifts and the atomic spectroscopic structures for other Mg-like ions with twelve extranuclear electrons.关键词
同位素位移/多组态相互作用/自洽场/镁原子Key words
isotope shift/multi-configuration interaction/self-consistent field/magnesium atom引用本文复制引用
余庚华,刘鸿,赵朋义,徐炳明,高当丽,朱晓玲,杨维..采用相对论多组态Dirac-Hartree-Fock方法对Mg原子同位素位移的理论研究[J].物理学报,2017,66(11):71-77,7.基金项目
Project supported by the National Natural Science Foundations of China (Grant Nos.11304093,11604253),the Plan Project of Youth Science and Technology New Star of Shaanxi Province (Grant No.2015KJXX-33),and the Fund of the Scientific Research Foundation of Sichuan Provincial Department of Education (Grant No.14ZB0375).国家自然科学基金(批准号:11304093,11604253)、陕西省青年科技新星项目(批准号:2015KJXX-33)和四川省教育厅科研基金(批准号:14ZB0375)资助的课题. （Grant Nos.11304093,11604253）
