Contreras-García J, Cardenas Carlos
Laboratoire de Chimie Théorique, UPMC, Sorbonne Universités and CNRS, 75005, Paris, France.
Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, 7800024, Santiago, Chile.
J Mol Model. 2017 Aug 25;23(9):271. doi: 10.1007/s00894-017-3434-5.
Conceptual DFT and quantum chemical topology provide two different approaches based on the electron density to grasp chemical concepts. We present a model merging both approaches, in order to obtain physical properties from chemically meaningful fragments (bonds, lone pairs) in the solid. One way to do so is to use an energetic model that includes chemical quantities explicitly, so that the properties provided by conceptual DFT are directly related to the inherent organization of electrons within the regions provided by topological analysis. An example of such energy model is the bond charge model (BCM) by Parr and collaborators. Bonds within an ELF-BCM coupled approach present very stable chemical features, with a bond length of ca. 1 Å and 2[Formula: see text]. Whereas the 2[Formula: see text] corroborate classical views of chemical bonding, the fact that bonds always expand along 1 Å introduces the concept of geometrical transferability and enables estimating crystalline cell parameters. Moreover, combining these results with conceptual DFT enables deriving a model for the band gap where the chemical hardness of a solid is given by the bond properties, charge, length, and a Madelung factor, where the latter plays the major role. In short, the fundamental gap of zinc-blende solids can be understood as given by a 2[Formula: see text] bond particle asymmetrically located on a 1 Å length box and electrostatically interacting with other bonds and with a core matrix. This description is able to provide semi-quantitative insight into the band gap of zinc-blende semiconductors and insulators on equal footing, as well as a relationship between band gap and compressibility. In other words, merging these different approaches to bonding enables to connect measurable macroscopic behavior with microscopic electronic structure properties and to obtain microscopic insight into the chemical origin of band gaps, whose prediction is still nowadays a difficult task. Graphical Abstract Conceptual DFT couples to quatum chemcial topology to explain the band gap of zinc-blende solids.
概念性密度泛函理论（DFT）和量子化学拓扑学基于电子密度提供了两种不同的方法来理解化学概念。我们提出了一个融合这两种方法的模型，以便从固体中有化学意义的片段（键、孤对电子）中获得物理性质。一种实现方法是使用一个明确包含化学量的能量模型，这样概念性DFT提供的性质就与拓扑分析所确定区域内电子的固有组织直接相关。这种能量模型的一个例子是帕尔及其合作者提出的键电荷模型（BCM）。在扩展拉格朗日密度泛函-键电荷模型（ELF-BCM）耦合方法中的键呈现出非常稳定的化学特征，键长约为1 Å和2[公式：见原文]。虽然2[公式：见原文]证实了化学键的经典观点，但键总是沿1 Å扩展这一事实引入了几何转移性的概念，并能够估算晶体的晶胞参数。此外，将这些结果与概念性DFT相结合能够推导出一个带隙模型，其中固体的化学硬度由键的性质、电荷、长度以及一个马德隆因子决定，后者起主要作用。简而言之，闪锌矿型固体的基本带隙可以理解为是由一个不对称地位于1 Å长盒子上的2[公式：见原文]键粒子与其他键以及与一个核心矩阵发生静电相互作用所导致的。这种描述能够在同等基础上对闪锌矿型半导体和绝缘体的带隙提供半定量的见解，以及带隙与可压缩性之间的关系。换句话说，融合这些不同的键合方法能够将可测量的宏观行为与微观电子结构性质联系起来，并获得对带隙化学起源的微观见解，而带隙的预测至今仍是一项艰巨的任务。图形摘要 概念性DFT与量子化学拓扑学相结合以解释闪锌矿型固体的带隙。
