Marenich Aleksandr V, Boggs James E
Institute for Theoretical Chemistry, Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA.
J Phys Chem A. 2007 Nov 8;111(44):11214-20. doi: 10.1021/jp070495f. Epub 2007 May 1.
This paper addresses some advances in the theoretical description of molecular spectroscopy beyond the Born-Oppenheimer adiabatic approximation. A solution of the nuclear dynamics problem complicated by the EE Jahn-Teller effect and spin-orbit coupling is considered for the case of the CF3O and CF3S radicals, all the model parameters being obtained solely from ab initio calculations without any adjustment to experimental numbers. Vibrational and vibronic model parameters were calculated at the equation-of-motion coupled cluster level of theory with basis sets of triple-zeta quality. The spin-orbit coupling in X 2E CF3O and CF3S was parametrized by means of a perturbative solution of the full Breit-Pauli spin-orbit operator. Spin-vibronic eigenvalues and eigenfunctions were computed in a basis set of products of electronic, electron spin, and vibrational functions. Results demonstrate the importance of explicit inclusion of the spin-orbit coupling and at least cubic Jahn-Teller terms in the model Hamiltonian for the high precision evaluation of spin-vibronic energy levels of CF3O and CF3S. The theoretical results support and complement the spectroscopic data observed for these species.
本文论述了超越玻恩-奥本海默绝热近似的分子光谱理论描述方面的一些进展。对于CF3O和CF3S自由基的情况，考虑了因电-电子 Jahn-Teller 效应和自旋-轨道耦合而变得复杂的核动力学问题的解决方案，所有模型参数均仅从从头算计算中获得，无需对实验数据进行任何调整。在运动方程耦合簇理论水平上，使用三重ζ质量的基组计算振动和振转模型参数。X 2E CF3O和CF3S中的自旋-轨道耦合通过全 Breit-Pauli 自旋-轨道算符的微扰解进行参数化。在电子、电子自旋和振动函数乘积的基组中计算自旋振转本征值和本征函数。结果表明，在模型哈密顿量中明确包含自旋-轨道耦合和至少三次 Jahn-Teller 项对于高精度评估CF3O和CF3S的自旋振转能级非常重要。理论结果支持并补充了这些物种的光谱数据。
