Kasper Joseph M, Li Xiaosong
Department of Chemistry, University of Washington, Seattle, Washington, USA.
J Comput Chem. 2020 Jun 15;41(16):1557-1563. doi: 10.1002/jcc.26196. Epub 2020 Mar 27.
While the natural transition orbital (NTO) method has allowed electronic excitations from time-dependent Hartree-Fock and density functional theory to be viewed in a traditional orbital picture, the extension to multicomponent molecular orbitals such as those used in relativistic two-component methods or generalized Hartree-Fock (GHF) or generalized Kohn-Sham (GKS) is less straightforward due to mixing of spin-components and the inherent inclusion of spin-flip transitions in time-dependent GHF/GKS. An extension of single-component NTOs to the two-component framework is presented, in addition to a brief discussion of the practical aspects of visualizing two-component complex orbitals. Unlike the single-component analog, the method explicitly describes the spin and frequently obtains solutions with several significant orbital pairs. The method is presented using calculations on a mercury atom and a CrO Cl complex.
虽然自然跃迁轨道（NTO）方法使得从含时 Hartree-Fock 和密度泛函理论得到的电子激发能够在传统轨道图景中得以展现，但向多组分分子轨道的扩展，比如相对论双组分方法、广义 Hartree-Fock（GHF）或广义 Kohn-Sham（GKS）中所使用的那些轨道，就不那么直接了，这是因为自旋组分的混合以及含时 GHF/GKS 中固有包含的自旋翻转跃迁。除了对可视化双组分复杂轨道的实际方面进行简要讨论之外，还提出了单组分 NTO 向双组分框架的扩展。与单组分类似物不同，该方法明确描述了自旋，并且经常会得到具有几个重要轨道对的解。通过对汞原子和 CrOCl 配合物的计算来展示该方法。
