Jabłoński Mirosław
Department of Quantum Chemistry, Faculty of Chemistry, Nicolaus Copernicus University in Toruń, 7-Gagarina Street, 87-100, Toruń, Poland.
J Comput Chem. 2018 Oct 5;39(26):2183-2195. doi: 10.1002/jcc.25532. Epub 2018 Oct 9.
The goal of the article is to revive discussion on the interpretation of bond paths linking distant atoms, particularly tracing weak interactions in dimers. According to the Pendás' concept of privileged exchange channel, a bond path is formed between this pair of competing atoms, which is associated with larger value of the exchange energy. We point out that, due to the short-range nature of the exchange energy, bond paths linking distant atoms clearly become doubtful indicators of dominant intermolecular interactions, particularly if some other characteristics (geometric, spectroscopic, based on electrostatic parameters, etc.) indicate other intermolecular interactions as dominant. Several such cases are thoroughly investigated. We show that electrostatic parameters are much more reliable indicators of dominant intermolecular interactions than bond paths. Then, we pay attention that the presence of ("unexpected", i.e., not necessarily indicating dominant intermolecular interactions) bond paths between pairs of atoms featuring highly expanded charge distributions can be easily explained by visual exploration of isodensity contour plots. As always pointing in the direction of the steepest increase, the gradient vector of the electron density favors areas of its high values gaining higher exchange energy, yet being blind to highly electron deficient areas nearby, which, however, can quite often be involved in dominant intermolecular interactions as strongly suggested by many other bonding analysis. We also suggest that an interatomic component of Hellmann-Feynman force would most likely be the most reliable indicator of attractive or repulsive character of individual interatomic interaction. © 2018 Wiley Periodicals, Inc.
本文的目的是重启关于连接远距离原子的键径解释的讨论，特别是追踪二聚体中的弱相互作用。根据彭达斯（Pendás）的特权交换通道概念，在这对竞争原子之间形成了一条键径，它与较大的交换能值相关。我们指出，由于交换能的短程性质，连接远距离原子的键径显然成为主要分子间相互作用的可疑指标，特别是当一些其他特征（几何、光谱、基于静电参数等）表明其他分子间相互作用为主导时。对几个这样的案例进行了深入研究。我们表明，静电参数比键径更可靠地指示主要分子间相互作用。然后，我们注意到，在具有高度扩展电荷分布的原子对之间存在（“意外的”，即不一定表明主要分子间相互作用）键径，可以通过对等密度等高线图的可视化探索轻松解释。电子密度的梯度向量总是指向增加最陡峭的方向，有利于其高值区域获得更高的交换能，但对附近高度缺电子区域视而不见，然而，正如许多其他键合分析强烈表明的那样，这些区域经常参与主要分子间相互作用。我们还建议，赫尔曼 - 费曼力的原子间分量很可能是单个原子间相互作用吸引或排斥特性的最可靠指标。© 2018威利期刊公司。
