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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The Resonance Energy of Benzene: A Revisit
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The Resonance Energy of Benzene: A Revisit

机译：苯的共振能：再探

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Zielinski and van Lenthe recently extended the block-localized wave function (BLW) method by introducing the resonating BLW (RBLW) method and performed test calculations on hexagonal H6 and benzene [J. Phys. Chem. A 2008, 112, 13197]. However, the Paulings resonance energies from their RBLW and ab initio valence bond (VB) calculations were greatly underestimated largely due to the imperfect use of either oneelectron orbitals (method ) delocal) or resonance structures (method ) local). Whereas it has been well recognized that electronic resonance within a molecular system plays a stabilizing role, there are many indirect experimental evidences available to evaluate the resonance energy and, thus, to justify computational results. Here we used the BLW method, which can be regarded as the simplest variant of modern ab initio VB theory, to re-evaluate the resonance energy of benzene at the B3LYP level, following the original definition by Pauling and Wheland, who obtained the resonance energy by subtracting the actual energy of the molecule in question from that of the most stable contributing structure. The computed vertical resonance energy (or quantum mechanical resonance energy) in benzene is 88.8, 92.2, or 87.9 kcal/mol with the basis sets of 6-31G(d), 6-311+G(d,p), or cc-pVTZ, respectively, while the adiabatic resonance energy (or theoretical resonance energy) is 61.4, 63.2, or 62.4 kcal/mol, exhibiting insignificant basis set dependency for moderate basis sets. In line with predictions, the geometry optimization of the elusive cyclohexatriene (i.e., the Kekule structure) with the BLW method also resulted in carbon-carbon bond lengths (e.g., 1.322 and 1.523 A with the cc-pVTZ basis set) comparable to those in ethylene or ethane.
机译：Zielinski和van Lenthe最近通过引入共振BLW（RBLW）方法扩展了块局部波函数（BLW）方法，并对六边形H6和苯进行了试验计算[J.物理化学A 2008，112，13197]。但是，鲍林斯的RBLW和从头算价键（VB）计算得出的共振能被大大低估了，这在很大程度上是由于不完全使用一个电子轨道（方法）或局部共振结构（方法）所致。众所周知，分子系统内的电子共振起稳定作用，但是有许多间接的实验证据可用来评估共振能，从而证明计算结果的合理性。在这里，我们根据Pauling和Wheland最初的定义，使用了BLW方法，可以将其视为现代从头算VB理论的最简单变体，以B3LYP水平重新评估苯的共振能。从最稳定的贡献结构中减去实际分子的能量。以6-31G（d），6-311 + G（d，p）或cc-为基础计算的苯的垂直共振能量（或量子力学共振能量）为88.8、92.2或87.9 kcal / mol pVTZ分别为绝热共振能量（或理论共振能量）为61.4、63.2或62.4 kcal / mol，对中等基数集显示不重要的基集依赖性。与预测相符，采用BLW方法对难以捉摸的环己三烯（即Kekule结构）进行几何优化，其碳-碳键长（例如，使用cc-pVTZ基集的1.322和1.523 A）可与乙烯或乙烷。

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