Somogyi W, Yurchenko S N, Yachmenev A
Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT London, United Kingdom.
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany and Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
J Chem Phys. 2021 Dec 7;155(21):214303. doi: 10.1063/5.0063256.
We present a unified variational treatment of the electric quadrupole (E2) matrix elements, Einstein coefficients, and linestrengths for general open-shell diatomic molecules in the general purpose diatomic code Duo. Transformation relations between the Cartesian representation (typically used in electronic structure calculations) to the tensorial representation (required for spectroscopic applications) of the electric quadrupole moment components are derived. The implementation has been validated against accurate theoretical calculations and experimental measurements of quadrupole intensities of H available in the literature. We also present accurate electronic structure calculations of the electric quadrupole moment functions for the XΣ electronic states of CO and HF, as well as for the aΔ-bΣ quadrupole transition moment of O with the MRCI level of theory. Accurate infrared E2 line lists for CO and HF are provided. A demonstration of spectroscopic applications is presented by simulating E2 spectra for CO, HF, and O (Noxon aΔ-bΣ band).
我们在通用双原子程序Duo中，对一般开壳层双原子分子的电四极矩（E2）矩阵元、爱因斯坦系数和谱线强度进行了统一的变分处理。推导了电四极矩分量在笛卡尔表示（通常用于电子结构计算）与张量表示（光谱应用所需）之间的变换关系。该实现已通过与文献中H的四极强度的精确理论计算和实验测量进行验证。我们还采用MRCI理论水平，对CO和HF的XΣ电子态以及O的aΔ - bΣ四极跃迁矩的电四极矩函数进行了精确的电子结构计算。提供了CO和HF精确的红外E2谱线表。通过模拟CO、HF和O（Noxon aΔ - bΣ带）的E2光谱展示了光谱应用。
