从头计算研究BCl+基态和激发态的势能曲线和光谱性质

基于相关一致极化4zeta(aug-cc-pVQZ)基组, 应用量子化学从头计算中高水平的多参考组态相互作用方法计算了BCl⁺ 两个离解极限B⁺(¹S_g)+Cl(²P_u)和B (²P_u)+Cl⁺ (³P_g)的14个Λ-S态势能曲线. 在计算中考虑了Davidson修正(+Q)和标量相对论效应, 并首次在计算中考虑了BCl⁺ 的旋轨耦合效应, 获得了由能量最低的4个Λ-S态分裂出的7个Ω 态. 计算结果表明相同对称性的Ω 态的势能曲线存在着非常明显的避免交叉. 通过分析Λ-S态的电子结构, 得到了各态的电子跃迁特性, 并确认了电子态的多组态性质. 使用LEVEL程序通过求解径向的Schrödinger方程得到了束缚Λ-S 和Ω态的光谱参数D_e, R_e, T_e, ω_e, ω_eχ_e和B_e. 通过和已有的Λ-S态X²∑⁺ 的实验数据进行对比发现, 本文所得的计算结果与实验结果非常一致. 而文中其他电子态的光谱参数均为首次报道.关键词：势能曲线光谱参数多参考组态相互作用方法旋轨耦合

Ab initio calculation on the potential energy curves and spectroscopic properties of the low-lying excited states of BCl

The high level quantum chemistry ab initio multi-reference configuration interaction method with reasonably large aug-cc-pVQZ basis sets is used to calculate the potential energy curves of 14 Λ-S states of BCl⁺ radical correlated to the dissociation limit B⁺(¹S_g)+Cl(²P_u) and B(²P_u) +Cl⁺(³P_g). In order to get the better potential energy curves, the Davidson correction and scalar relativistic effect are taken into consideration. The spin-orbit interaction is first considered, which makes the lowest 4 Λ-S states split to 7 Ω states. The calculational results show that the avoided crossing rule exists between the Ω states of the same symmetry. The analyses of the electronic structures of Λ-S states determine the electronic transition of each state and demonstrates that the Λ-S electronic states are multi-configurational in nature. Then the spectroscopic constants of the bound Λ-S and Ω states are obtained by solving the radial Schrödinger equation. By comparison with experimental results, the spectroscopic constants of ground states are in good agreement with the observed values. The remaining computational results are reported for the first time.