Dunning Thom H, Xu Lu T, Takeshita Tyler Y, Lindquist Beth A
Department of Chemistry, University of Illinois at Urbana-Champaign , 600 S. Mathews Avenue, Urbana, Illinois 61801, United States.
J Phys Chem A. 2016 Mar 24;120(11):1763-78. doi: 10.1021/acs.jpca.5b12335. Epub 2016 Mar 7.
In this article we describe the unique insights into the electronic structure of molecules provided by generalized valence bond (GVB) theory. We consider selected prototypical hydrocarbons as well as a number of hypervalent molecules and a set of first- and second-row valence isoelectronic species. The GVB wave function is obtained by variationally optimizing the orbitals and spin coupling in the valence bond wave function. The GVB wave function is a generalization of the Hartree-Fock (HF) wave function, lifting the double occupancy restriction on a subset of the HF orbitals as well as the associated orthogonality and spin coupling constraints. The GVB wave function includes a major fraction (if not all) of the nondynamical correlation energy of a molecule. Because of this, GVB theory properly describes bond formation and can answer one of the most compelling questions in chemistry: How are atoms changed by molecular formation? We show that GVB theory provides a unified description of the nature of the bonding in all of the above molecular species as well as contributing new insights into the well-known, but poorly understood, first-row anomaly.
在本文中，我们描述了广义价键（GVB）理论对分子电子结构的独特见解。我们考虑了选定的典型碳氢化合物以及一些超价分子和一组第一周期和第二周期的价电子等电子体。通过对价键波函数中的轨道和自旋耦合进行变分优化来获得GVB波函数。GVB波函数是哈特里 - 福克（HF）波函数的推广，它解除了对HF轨道子集的双占据限制以及相关的正交性和自旋耦合约束。GVB波函数包含了分子非动态相关能的主要部分（如果不是全部的话）。因此，GVB理论能够恰当地描述键的形成，并能回答化学中最引人注目的问题之一：分子形成如何改变原子？我们表明，GVB理论对上述所有分子物种的键合本质提供了统一的描述，同时也为众所周知但理解不足的第一周期反常现象提供了新的见解。
