Martín Pendás Ángel, Francisco Evelio, Suárez Dimas, Costales Aurora, Díaz Natalia, Munárriz Julen, Rocha-Rinza Tomás, Guevara-Vela José Manuel
Depto. Química Física y Analítica, Universidad de Oviedo, 33006 Oviedo, Spain.
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Delegación Coyoacán, México City C.P. 04510, Mexico.
Phys Chem Chem Phys. 2023 Apr 12;25(15):10231-10262. doi: 10.1039/d2cp05540f.
In this perspective, we review some recent advances in the concept of atoms-in-molecules from a real space perspective. We first introduce the general formalism of atomic weight factors that allows unifying the treatment of fuzzy and non-fuzzy decompositions under a common algebraic umbrella. We then show how the use of reduced density matrices and their cumulants allows partitioning any quantum mechanical observable into atomic or group contributions. This circumstance provides access to electron counting as well as energy partitioning, on the same footing. We focus on how the fluctuations of atomic populations, as measured by the statistical cumulants of the electron distribution functions, are related to general multi-center bonding descriptors. Then we turn our attention to the interacting quantum atom energy partitioning, which is briefly reviewed since several general accounts on it have already appeared in the literature. More attention is paid to recent applications to large systems. Finally, we consider how a common formalism to extract electron counts and energies can be used to establish an algebraic justification for the extensively used bond order-bond energy relationships. We also briefly review a path to recover one-electron functions from real space partitions. Although most of the applications considered will be restricted to real space atoms taken from the quantum theory of atoms in molecules, arguably the most successful of all the atomic partitions devised so far, all the take-home messages from this perspective are generalizable to any real space decompositions.
从实空间角度出发，我们回顾了分子中原子概念的一些最新进展。我们首先介绍原子权重因子的一般形式，它能在一个共同的代数框架下统一模糊和非模糊分解的处理。接着我们展示了如何利用约化密度矩阵及其累积量将任何量子力学可观测量划分为原子或基团贡献。这种情况使得在相同基础上进行电子计数和能量划分成为可能。我们关注通过电子分布函数的统计累积量测量的原子布居涨落如何与一般的多中心键描述符相关。然后我们将注意力转向相互作用量子原子能量划分，由于已有几篇关于它的一般性论述出现在文献中，故在此简要回顾。更多关注的是其在大系统中的近期应用。最后，我们考虑如何用一种提取电子计数和能量的通用形式来为广泛使用的键级 - 键能关系建立代数依据。我们还简要回顾了从实空间划分中恢复单电子函数的一条途径。尽管所考虑的大多数应用将限于取自分子中原子量子理论的实空间原子，这可以说是迄今为止设计出的所有原子划分中最成功的，但从这个角度得到的所有关键信息都可推广到任何实空间分解。
