基于组态相互作用方法对AuB分子低激发态电子结构和光学跃迁性质的研究

Study of electronic structure and optical transition properties of low-lying excited states of AuB molecules based on configuration interaction method

因为AuB分子的电子态信息缺乏相关实验测量,本文采用高精度的组态相互作用方法开展对AuB分子激发态电子结构的研究,计算得到12个Λ-S态的势能曲线.基于势能曲线,束缚态的光谱常数通过数值求解薛定谔方程获得.计算还包括部分低激发态的偶极矩,展示了分子不同电子态的电荷分布信息.在计算中也考虑了自旋轨道耦合效应对电子态的影响.其中能量最低的4个Λ-S态之间的自旋轨道耦合矩阵元,因为自旋轨道耦合的影响,这4个Λ-S态会劈裂为12个Ω态.由于自旋轨道耦合矩阵元并没有交叉现象,所以这4个Λ-S态不存在预解离的情况.本文最后计算得到Ω基态A^(1)П_(1)和第一激发态X^(1)∑_(0)+的光学跃迁矩阵元等信息,分析Franck-Condon因子和辐射寿命,发现AuB分子中该光吸收模式被激光冷却的可能性较小.本文数据集可在https://www.doi.org/10.57760/sciencedb.j00213.00009中访问获取.

High-level configuration interaction method including the spin-orbit coupling is used to investigate the low-lying excited electronic states of AuB that is not reported experimentally.The electronic structure in our work is preformed through the three steps stated below.First of all,Hartree-Fock method is performed to compute the singlet-configuration wavefunction as the initial guess.Next,we generate a multi-reference wavefunction by using the state-averaged complete active space self-consistent field(SACASSCF).Finally,the wavefunctions from CASSCF are utilized as reference,the exact energy point values are calculated by the explicitly correlated dynamic multi-reference configuration interaction method(MRCI).The Davidson correction(+Q)is put forward to solve the size-consistence problem caused by the MRCI method.To ensure the accuracy,the spin-orbit effect and correlation for inner shell electrons and valence shell electrons are considered in our calculation.The potential energy curves of 12Λ-S electronic states are obtained.According to the explicit potential energy curves,we calculate the spectroscopic constants through solving radial Schrödinger equation numerically.We analyze the influence of electronic state configuration on the dipole moment by using the variation of dipole moment with nuclear distance.The spin-orbit matrix elements for parts of low-lying exciting states are computed,and the relation between spin-orbit coupling and predissociation is discussed.The predissociation is analyzed by using the obtained spin-orbit matrix elements of the 4Λ-S states which spilt into 12Ωstates.It indicates that due to the absence of the intersections between the curves of spin-orbit matrix elements related with the 4 low-lyingΛ-S states,the predissociation for these low-lying exciting states will not occur.Finally,the properties of optical transition between the groundΩstate A^(1)П_(1)and first excitedΩstate X^(1)∑_(0)+are discussed in laser-cooling filed by analyzing the Franck-Condon factors and radiative lifetime.And the transition dipole moment is also calculated.But our results reveal that the AuB is not an ideal candidate for laser-cooling.In conclusion,this work is helpful in deepening the understanding of AuB,especially the structures of electronic states,interaction between excited states,and optical transition properties.All the data presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00213.00009.