Department of Chemistry and Physics , Indiana State University , Terre Haute , Indiana 47809 , United States.
Theoretical Chemistry Institute and Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.
J Chem Theory Comput. 2019 Feb 12;15(2):916-921. doi: 10.1021/acs.jctc.8b00948. Epub 2019 Jan 18.
We describe a practical algorithm for calculating NBO-based "resonance natural bond orbitals" (RNBOs) that can accurately describe the localized bond shifts of a reactive chemical process. Unlike conventional NBOs, the RNBOs bear no fixed relationship to a particular Lewis-structural bonding pattern but derive instead from the natural resonance theory (NRT)-based manifold of all bonding patterns that contribute significantly to resonance mixing (and associated multichannel reactivity) at a chosen point of the potential energy surface. The RNBOs typically retain familiar localized Lewis-structural character for stable near-equilibrium species, yet they freely adopt multicenter character as required to satisfy Pople's prerequisite that no allowed computational basis set should be inherently biased toward a particular nuclear arrangement or bonding pattern. A simple numerical application to intramolecular Claisen rearrangement demonstrates the computational and conceptual advantages of describing reactive bond-shifts with RNBOs rather than other conventional NBO- or MO-based expansion sets.
我们描述了一种实用的算法，用于计算基于 NBO 的“共振自然键轨道”（RNBO），该算法可以准确描述反应性化学过程中的局部键移动。与传统的 NBO 不同，RNBO 与特定的路易斯结构键合模式没有固定关系，而是源自自然共振理论（NRT）基础上的所有显著贡献于共振混合（以及相关的多通道反应性）的键合模式的流形，在势能表面的选定点。RNBO 通常保留稳定近平衡物种的熟悉的局部路易斯结构特征，但它们可以自由采用多中心特征，以满足 Pople 的前提要求，即没有允许的计算基组应该固有地偏向于特定的核排列或键合模式。对分子内 Claisen 重排的简单数值应用表明，用 RNBO 而不是其他基于传统 NBO 或 MO 的展开集来描述反应性键移动具有计算和概念上的优势。
