物理方面的粒子间关联和化学键：共价性、$\textit{versus}$原子性和离子性
Interparticle correlations and chemical bonding from physical side: Covalency $\textit{versus}$ atomicity and ionicity
摘要：
在本章中，我们以最简单的分子为例，重新考察$\textit{covalency}$和$\textit{ionicity}$的概念。首先，从Heitler-London模型中$H_2$分子的两粒子波函数的精确表达式出发，证明了原子间距离较大时共价性的非物理行为，在标准定义范围内，共价性在分离原子的极限下达到最大值。其次，我们通过引入$\textit{atomicity}$的概念来纠正这一缺陷，并在此基础上定义了$\textit{true}$（内在）$\textit{covalency}$，同时保留了$\textit{ionicity}$的精确概念。我们连接引入的原子性的发病Mott-Hubbard本地化，通过这里从凝聚态物质中的既定概念。当原子间距离超过局域化阈值时，从分子态到原子态的演化迅速发展。这一简要概述的目的是作为教学性质，但定量分析的情况下，$H_2$分子。最后，我们以腺嘌呤-酪胺对为例，对相关的氢键情况给出了一个类似的模型。在方法论上，该方法是基于结合第一（波动力学）和第二量子化成一个单一的方案的正式描述。
英文摘要：
In this Chapter we reexamine the concept of $\textit{covalency}$ and $\textit{ionicity}$ on example of the simplest molecules. First, starting from the exact expression for the two-particle wave function in the case of $H_2$ molecule within the Heitler-London model, we demonstrate an unphysical behavior of the covalency at large interatomic distance which, within standard definition, reaches the maximal value in the limit of separated atoms. Second, we correct this deficiency by introducing the concept of $\textit{atomicity}$, with the help of which, we define the $\textit{true}$ (intrinsic) $\textit{covalency}$, as well as retain the precise concept of $\textit{ionicity}$. We connect the introduced atomicity to the onset of Mott-Hubbard localization, adopted here from the well established notion in the condensed matter. The evolution from the molecular to atomic states develops rapidly with interatomic distance beyond the localization threshold. This brief overview is intented as pedagogical in nature, nonetheless is analyzed quantitatively for the case of $H_2$ molecule. At the end, we outline a similar-type of model for the related case of the hydrogen bond on example of adenine-tymine pair. Methodologically, the approach is based on combining the first- (wave mechanics) and second-quantization into a single scheme of formal description.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
