Lee Timothy J, Fortenberry Ryan C
MS245-3, Planetary Systems Branch, Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, CA 94035, USA.
Department of Chemistry & Biochemistry, University of Mississippi, University, MS 38677-1848, USA.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Mar 5;248:119148. doi: 10.1016/j.saa.2020.119148. Epub 2020 Nov 4.
More than 30 years ago two groups independently identified a problem in the calculation of the out-of-plane bending (OPB) vibrational frequencies for the ethylene molecule using correlated electronic structure methods. Several studies have been done in the meantime to try and understand and resolve this issue. In so doing this problem has been found to be far more insidious than previously realized for acetylene-like and benzene-like molecules, which can become non-linear and non-planar, respectively. The one common feature that all molecules with this problem have is that they contain CC multiple bonds, and so this has been called the "CC multiple bond OPB frequency issue" or "the CC OPB problem." Various explanations for this problem have been advanced such as basis set superposition error, basis set incompleteness error, linear dependences in the basis set, proper balancing of the basis set between saturation and inclusion of higher angular momentum functions, etc. and possible solutions have arisen from these suggestions. All of these proposed solutions, however, amount to one main point connecting them all: modifying the one-particle basis set in some way. None of the explanations that have been advanced, however, really fit all of the data for all of the molecules where this problem has been identified, and importantly, none of these diagnostic tests have been applied to similar molecules where this issue does not appear. In this review, the studies over the last 30 plus years are discussed and relevant data from each of these is compared and contrasted. It is hoped that by collecting and analyzing the data from these studies a path forward to understanding and resolving this issue will become evident.
30多年前，两个研究小组独立发现，使用相关电子结构方法计算乙烯分子的面外弯曲（OPB）振动频率时存在一个问题。在此期间，已经进行了几项研究，试图理解和解决这个问题。在此过程中，人们发现这个问题比之前意识到的对于类似乙炔和类似苯的分子来说要隐蔽得多，这两类分子可能分别变得非线性和非平面。所有存在这个问题的分子的一个共同特征是它们都含有碳碳多重键，因此这被称为“碳碳多重键OPB频率问题”或“碳碳OPB问题”。针对这个问题已经提出了各种解释，比如基组叠加误差、基组不完整性误差、基组中的线性相关性、基组在饱和性和包含更高角动量函数之间的适当平衡等等，并且从这些建议中也产生了可能的解决方案。然而，所有这些提出的解决方案都归结为一个将它们联系在一起的主要观点：以某种方式修改单粒子基组。然而，已经提出的所有解释都不能真正适用于所有已发现这个问题的分子的所有数据，重要的是，这些诊断测试都没有应用于不存在这个问题的类似分子。在这篇综述中，讨论了过去30多年的研究，并对其中每一项研究的相关数据进行了比较和对比。希望通过收集和分析这些研究的数据，一条理解和解决这个问题的前进道路将变得清晰。
