GeO分子激发态的电子结构和跃迁性质的组态相互作用方法研究

Configuration interaction study on electronic structures and transitional properties of excited states of GeO molecule

应用多参考组态相互作用方法计算了GeO分子的第一解离极限(Ge(3Pg)+O(3Pg))对应的18个-S电子态的电子结构.计算中纳入了Ge原子的3d轨道电子的内壳层-价壳层电子关联效应、标量相对论效应和Davidson修正.基于计算的电子态的电子结构,通过求解径向Schrdinger方程获得了束缚电子态的光谱常数Re,Te,ωe,ωeχe,B e,理论计算给出的这些电子态的光谱常数与之前的实验结果符合得很好.计算了电子态的电偶极矩随核间距的变化,分析了电子态的组态成分的变化对电偶极矩的影响.计算的势能曲线表明,激发态A1∏,11,D1Σ,a3∏,a′3Σ+,d3△和e3Σ的绝热激发能密集地分布于26000—37000 cm 1范围内,这些密集分布的电子态之间的相互作用对振动波函数有明显扰动作用.借助于激发态之间的自旋-轨道耦合矩阵元,阐明了邻近的激发态对A1和a3的扰动作用.基于计算的A1∏—X1Σ+和A′1Σ+—X1Σ+跃迁的电偶极跃迁矩和Franck-Condon因子,给出了A1和A′1Σ+态的最低的六个振动能级的辐射寿命.

GeO molecule, which plays an important role in fabricating integrated optics and semiconductor components, has received much attention. However, the electronic state density of the molecule is very large, and the electric structures and transitional properties of the molecule have not been well investigated. In this work, the 18 A-S states correlated to the lowest dissociation limit （Ce（3pg）＋O（3pg）） are calculated by a complete active space self-consistent field （CASSCF） method, through using the previous Hatree-Fock molecular orbitals as the starting orbitals. Furthermore, we take all configurations in the configuration interaction expansions of the CASSCF wave functions as a reference configuration, and calculate the energies of the 18A-S states by a high-level multireference configuration interaction method. The core- valence correlation effect of the 3d orbit of Ge atom, the scalar relativistic effect, and the Davidson correction are taken into consideration in the calculations. On the basis of the calculated potential energy curves of the bound and quasibound electronic states, the spectroscopic constants （R e, Te, w e, w e X e, and B e）, vibrational energy levels, vibrational wave functions, and Franck-Condon factors （FCFs） are obtained by solving the radical Schr6dinger equation. The computed spectroscopic constants of these electronic states are well consistent with previously available experimental results. We calculate the electric dipole moments of electronic states with different bound lengths, and analyze the influences of the variation of electron configuration on the electric dipole moment. The calculated potential energy curves indicate that the adiabatic transition energies of A^1Ⅱ,1^1∑^-,D^1△,a^3Ⅱ,a＇^3∑^＋,d^3△, and e3E-sates are located in a range of 26000-37000 cm 1 and the spin-orbit coupling of the states can obviously affect the corresponding vibrational wave functions. With the help of calculated spin-orbit coupling matrix elements, the perturbations of the nearby states to a3H and A^1П are discussed in detail. Our calculation results indicate that the spin-orbit coupling between A^1П and e^3∑- states has an evident perturbation on the v＇〉 4 vibrational levels of A^1П, and the v＇≥0 vibrational levels of a^3П state are perturbed by the crossing states A^1П＇∑＋和A＇^1∑^＋-X^1∑^＋ and D1△. On the basis of computed transition dipole moments and FCFs of A^1П-X^1∑^＋and A＇1^∑^＋-X1∑^＋ transitions, the radiative lifetimes of the six lowest vibrational levels of the two singlet excited states are computed.