Zn和Cd的卤化物分子的电子结构和光谱性质的理论研究

Due to an important role in the process that could contaminate the environment, zinc and cadmium halides have been a subject of extensive theoretical and experimental interest. Because of the coupling interactions between excited states which could affect the electronic structures and dissociation dynamics, the zinc and cadmium halide molecules have little spectral information. In our study we investigate the electronic structure and the spectroscopic property of all the electronic states of zinc and cadmium halide molecules correlating to the first two or three dissociation asymptotes by high-level ab initio calculations. The dominant contents are provided below. 1) The potential energy curves of zinc and cadmium halide molecules are calculated using the multireference configuration interaction method. With the aid of calculated potential energy curves, the spectroscopic parameters of bound states are obtained using the LEVEL program. With the aid of Λ-S compositional variation of Ω states, the influence of the spin-orbit coupling effect on the electronic structure of electronic state is analyzed. 2) The dipole moment functions are analyzed. The transition dipole moments, excitation energies, and the Franck-Condon factors between excited states and the ground state are calculated, and the radiative lifetimes of several low-lying vibrational states are obtained. On the basis of the obtained spin-orbit matrix elements, the influence of the spin-orbit coupling effect on the radiative transition is determined. The results of this project reveal more information on the electronic structures and spectroscopic properties, and provide more useful theoretical support for the experimental studies.

锌和镉的卤化物在环境污染中扮演重要的角色，已成为理论和实验上广泛关注的课题。由于激发态间的耦合效应对电子结构和预解离过程的影响，这类卤化物分子的光谱信息较少。本课题拟采用高精度从头算的方法对这类分子的最低二至三个解离通道对应的电子态进行电子结构和光谱性质的研究。主要研究内容如下: 1) 采用多参考组态相互作用方法研究分子的势能曲线，利用LEVEL程序拟合给出束缚态的光谱常数。借助于Ω态的Λ-S成分的变化，解释自旋-轨道耦合效应对分子电子态的电子结构的影响。2）分析各个电子态的电偶极矩变化规律，计算跃迁偶极矩、激发能和Franck-Condon因子，获得激发态较低的几个振动能级的辐射寿命。基于电子态间的自旋-轨道矩阵元，分析激发态间的耦合效应对辐射跃迁性质的影响。项目研究将加深对锌和镉的卤化物分子的电子结构和光谱性质的认识，为相关的实验提供理论参考。

含重金属元素的CdX(X=F, Cl, Br, I)，ZnY(Y=F, Cl, Br, I)和MH(M=Zn,Pb)分子在环境污染、化学反应和化学激光中扮演重要角色，已成为理论和实验上广泛关注的课题。由于激发态间的耦合效应使得这类分子的光谱指认较为困难，它们的光谱信息仍不完备。本课题采用高精度从头算对这类分子的低激发态的电子结构进行了研究，获得了它们的辐射跃迁特性和光谱数据。为了保证精确度，在理论计算中，我们考虑了Davidson修正、内壳层-价壳层关联效应、自旋-轨道耦合效应对电子结构的影响。本项目的具体研究成果如下：. 1. 采用多参考组态相互作用方法计算了CdX(X=F, Cl, Br, I)和ZnX(X=F, Cl, Br, I)分子的14个Λ-S态和考虑自旋-轨道效应后的30个Ω态势能曲线，应用数值方法获得了束缚态的光谱常数。给出了各个电子态的电偶极矩变化规律，分析了自旋-轨道耦合效应对B2Σ+1/2、C2Π1/2和22Π3/2的跃迁偶极矩的影响。给出了包含C2П和B2Σ+态的自旋-轨道矩阵元，分析了激发态之间的耦合效应对C2П态预解离的影响。最后，给出了电子态B2Σ+1/2、C2Π1/2和22Π3/2的垂直激发能和振子强度以及它们的较低的几个振动能级的辐射寿命。. 2. 采用多参考组态相互作用方法计算了MH(M=Zn,Pb)分子最低的四个离解限对应的Λ-Ѕ态的势能曲线和考虑自旋-轨道效应后的Ω态的势能曲线，应用数值方法得到了束缚态的光谱常数。分析了电子组态成分变化对电偶极矩和成键性质的影响。ZnH分子的C2Σ+束缚态是一个离子对态，借助自旋-轨道耦合矩阵元，分析了它与排斥态14Σ+和14Π相互作用导致的预解离。PbH分子的32Π和32Σ+态为准束缚态，对应于离子对解离极限Pb+(2Pu)+H-(1Sg)。最后，计算了它们的跃迁偶极矩、激发能和Franck-Condon因子，获得了低激发态的辐射寿命。. 项目研究加深了对含重金属元素的CdX(X=F, Cl, Br, I)，ZnY(Y=F, Cl, Br, I)和MH（M=Zn,Pb）分子的电子结构和光谱性质的认识，为后续相关的实验提供理论参考。