Qu Qianwei, Cooper Bridgette, Yurchenko Sergei N, Tennyson Jonathan
Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
J Chem Phys. 2021 Feb 21;154(7):074112. doi: 10.1063/5.0038527.
The rovibronic structure of AΣ, BΠ, and CΠ states of nitric oxide (NO) is studied with the aim of producing comprehensive line lists for its near ultraviolet spectrum. Empirical energy levels for the three electronic states are determined using a combination of the empirical measured active rotation-vibration energy level (MARVEL) procedure and ab initio calculations, and the available experimental data are critically evaluated. Ab initio methods that deal simultaneously with the Rydberg-like AΣ and CΠ and the valence BΠ state are tested. Methods of modeling the sharp avoided crossing between the BΠ and CΠ states are tested. A rovibronic Hamiltonian matrix is constructed using the variational nuclear motion program Duo whose eigenvalues are fitted to the MARVEL. The matrix also includes coupling terms obtained from the refinement of the ab initio potential energy and spin-orbit coupling curves. Calculated and observed energy levels agree well with each other, validating the applicability of our method and providing a useful model for this open shell system.
为了生成一氧化氮（NO）近紫外光谱的综合谱线列表，对其AΣ、BΠ和CΠ态的振转电子结构进行了研究。结合经验测量的活性转动-振动能级（MARVEL）程序和从头算计算，确定了这三个电子态的经验能级，并对现有实验数据进行了严格评估。测试了同时处理类里德堡AΣ和CΠ以及价BΠ态的从头算方法。测试了模拟BΠ和CΠ态之间尖锐避免交叉的方法。使用变分核运动程序Duo构建了一个振转电子哈密顿矩阵，其本征值与MARVEL拟合。该矩阵还包括从从头算势能和自旋-轨道耦合曲线的优化中获得的耦合项。计算得到的能级与观测到的能级吻合良好，验证了我们方法的适用性，并为这个开壳层系统提供了一个有用的模型。
