Bader Richard F W
Department of Chemistry, McMaster University, Hamilton, ON L7L 2T1, Canada.
J Phys Chem A. 2009 Sep 24;113(38):10391-6. doi: 10.1021/jp906341r.
This account takes to task papers that criticize the definition of a bond path as a criterion for the bonding between the atoms it links by mistakenly identifying it with a chemical bond. It is argued that the notion of a chemical bond is too restrictive to account for the physics underlying the broad spectrum of interactions between atoms and molecules that determine the properties of matter. A bond path on the other hand, as well as being accessible to experimental verification and subject to the theorems of quantum mechanics, is applicable to any and all of the interactions that account for the properties of matter. It is shown that one may define a bond path operator as a Dirac observable, making the bond path the measurable expectation value of a quantum mechanical operator. Particular attention is given to van der Waals interactions that traditionally are assumed to represent attractive interactions that are distinct from chemical bonding. They are assumed by some to act in concert with Pauli repulsions to account for the existence of condensed states of molecules. It is such dichotomies of interpretation that are resolved by the experimental detection of bond paths and the delineation of their properties in molecular crystals. Specific criticisms of the stabilization afforded by the presence of bond paths derived from spectroscopic measurements performed on dideuteriophenanthrene are shown to be physically unsound. The concept of a bond path as a "bridge of density" linking bonded atoms was introduced by London in 1928 following the definition of the electron density by Schrödinger in 1926. These papers marked the beginning of the theory of atoms in molecules linked by bond paths.
本文批评了一些论文，这些论文错误地将键径与化学键等同起来，从而批评了将键径定义为其所连接原子之间键合标准的做法。有人认为，化学键的概念过于局限，无法解释决定物质性质的原子和分子间广泛相互作用背后的物理原理。另一方面，键径不仅可以通过实验验证，还受制于量子力学定理，适用于任何和所有决定物质性质的相互作用。结果表明，可以将键径算符定义为狄拉克可观测量，使键径成为量子力学算符的可测量期望值。特别关注了范德华相互作用，传统上认为范德华相互作用代表了与化学键不同的吸引相互作用。一些人认为它们与泡利排斥力共同作用，以解释分子凝聚态的存在。正是通过键径的实验检测以及在分子晶体中对其性质的描绘，解决了这种解释上的二分法。对通过对二氘菲进行光谱测量得出的键径所提供的稳定性的具体批评被证明在物理上是不合理的。1926年薛定谔定义电子密度后，1928年伦敦引入了键径作为连接成键原子的“密度桥”的概念。这些论文标志着通过键径连接的分子中原子理论的开端。
