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首页> 外文期刊>Chemistry: A European journal >Topology of Electron Charge Density for Chemical Bonds from Valence Bond Theory: A Probe of Bonding Types
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Topology of Electron Charge Density for Chemical Bonds from Valence Bond Theory: A Probe of Bonding Types

机译：基于价键理论的化学键电子电荷密度拓扑：键类型的探讨

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摘要

To characterize the nature of bonding we derive the topological properties of the electron charge density of a variety of bonds based on ab initio valence bond methods. The electron density and its associated Laplacian are partitioned into covalent, ionic, and resonance components in the valence bond spirit. The analysis provides a density-based signature of bonding types and reveals, along with the classical covalent and ionic bonds, the existence of two-electron bonds in which most of the bonding arises from the covalentCionic resonance energy, so-called charge-shift bonds. As expected, the covalent component of the Laplacian at the bond critical point is found to be largely negative for classical covalent bonds. In contrast, for charge-shift bonds, the covalent part of the Laplacian is small or positive, in agreement with the weakly attractive or repulsive character of the covalent interaction in these bonds. On the other hand, the resonance component of the Laplacian is always negative or nearly zero, and it increases in absolute value with the charge-shift character of the bond, in agreement with the decrease of kinetic energy associated with covalentCionic mixing. A new interpretation of the topology of the total density at the bond critical point is proposed to characterize covalent, ionic, and charge-shift bonding from the density point of view.
机译：为了表征键的性质，我们基于从头价键方法得出了各种键的电子电荷密度的拓扑性质。在价键精神中，电子密度及其相关的拉普拉斯算子被分为共价，离子和共振成分。该分析提供了键类型的基于密度的特征，并揭示了经典的共价键和离子键以及双电子键的存在，其中大多数键是由共价的阳离子共振能产生的，即所谓的电荷转移键。不出所料，在键的临界点上，拉普拉斯算术中的共价成分对于经典的共价键而言很大程度上为负。相反，对于电荷转移键，拉普拉斯算子的共价部分较小或为正，这与这些键中共价相互作用的弱吸引或排斥特性相符。另一方面，拉普拉斯共振分量始终为负或接近零，并且其绝对值随键的电荷转移特性而增加，这与共价阳离子共混相关的动能降低是一致的。提出了对键临界点总密度拓扑结构的新解释，以从密度的角度表征共价键，离子键和电荷移位键。

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