考虑自旋-轨道耦合效应下SeH^-阴离子的光谱和跃迁性质  

Spectroscopic and transition properties of SeH^- anion including spin-orbit coupling

作　　者：万明杰[1] 柳福提[1] 黄多辉[1] Wan Ming-Jie;Liu Fu-Ti;Huang Duo-Hui(Faculty of Science,Yibin University,Yibin 644007,China)

机构地区：[1]宜宾学院理学部,宜宾644007

出　　处：《物理学报》2021年第3期69-77,共9页Acta Physica Sinica

基　　金：宜宾学院预研项目(批准号:2019YY06);计算物理四川省高等学校重点实验室开放基金(批准号:YBXYJSWL-ZD-2020-001)资助的课题。

摘　　要：采用高精度的从头算方法研究了SeH阴离子的基态(X1∑+)和低激发(a3Π,A1Π,b3∑+,21∑+)的势能曲线、偶极矩和跃迁偶极矩.在计算中考虑了价-芯(CV)电子关联、Davidson修正、标量相对论修正和自旋-轨道耦合效应(SOC).考虑了SOC效应后,b3∑0-+和b3∑1+态变为了弱束缚态.计算得到a3Π1X1∑0++,a3Π0+■X1∑0++和A1Π1■X1∑0++跃迁具有很大的跃迁偶极矩.这三种跃迁都同时具有高对角分布的弗兰克-康登因子f00及振动分支比R00.计算得到了a3Π1,a3Π0和A1Π1激发态的自发辐射寿命都很短,能够实现对SeH-阴离子的快速激光冷却.A1Π1■X1∑0-+跃迁为三能级跃迁,中间态的存在对构建准闭合的循环能级的影响可以忽略.驱动a3Π1■X1∑0++,a3Π0+■X1∑0++和A1Π1■X1∑0++跃迁进行激光冷却SeH-阴离子的激光波长都在可见光范围内.本文的结果为以后激光冷却SeH-阴离子的实验提供了部分理论参考.Potential energy curves(PECs),permanent dipole moments(PDMs)and transition dipole moments(TMDs)of five A-S states of SeH-anion are calculated by the MRCI+Q method with ACVQZ-DK basis set.The core-valence corrections,Davidson corrections,scalar relativistic corrections,and spin-orbit coupling(SOC)effects are also considered.In the CASSCF step,Se(ls2s2p3s3p)shells are put into the frozen orbitals,which are not optimized.Six molecular orbitals are chosen as active space,including H(ls)and Se(4s4p5s)shells,and eight electrons are distributed in a(4,1,1,0)active space,which is referred to as CAS(8,6),and the Se(3d)shell is selected as a closed-shell,which keeps doubly occupation.In the MRCI step,the remaining Se(3 d)shell is used for core-valence calculations of SeH-anion.The SOC effects are taken into account in the one-and twoelectron Breit-Pauli operators.The b^3∑^+ state is a repulsive state.Other excited states are bound,and all states possess two potential wells.The b^3∑0-^+ and b^3∑1^+ both turn into bound states when the SOC effect is considered.All spectroscopic parameters of∧-S states andΩstates are reported for the first time.The TDMs of the A^1Π^1■X^1∑0+^+,a^3Π^1■X^1∑0+^+,a^3Π0^+■X^1∑0+^+,A^1Π^1■a^3Π^1,and A^1Π^1■a^3Π0^+ transitions are also calculated.The TDMs of the A^1Π^1■X^1∑0+^+ and a^3Π^1■X^1∑0+^+ transitions are large in the Franck-Condon region,which are about -2.05 Debye(D)and 1.45 D at Re.Notably,the TDMs of the a^3Π0^+■X^1∑0+^+ transition cannot be ignored.The value of TDM at Re equals -0.15 D.Based on the accurately PECs and PDMs,the values of Franck-Condon factor fv’v",vibrational branching ratio Rv’v"and radiative coefficient of the a^3Π^1■X^1∑0+^+,a^3Π0^+■X^1∑0+^+,and A^1Π^1■X^1∑0+^+ transitions are also calculated.Highly diagonally distributed Franck-Condon factor f00 and the values of vibrational branching ratio R00 of the a^3Π^1(v’)■X^1∑0+^+(v"),a^3Π0+(v’)■X^1∑0+^+(v"),and A1Π1(v’)■X^1∑0+^+(v")transitio

关 键 词：自旋-轨道耦合效应 振动分支比 自发辐射寿命 激光冷却 

分 类 号：O641.1[理学—物理化学]