Topological analysis of Electron Localization Function (ELF) as a Tool for Understanding Electronic Structure

The chapter presents an overview of selected topological analysis of electron localization function (ELF) published worldwide, either important to the development of methodology or illustrating its applications to a variety of chemical problems such as type of bonding, electronic structure, reaction mechanisms, or chemical processes. The practical application of the ELF methodology is also presented using the H3N...HXeF molecular complex, alkali metal dimers, A2, alkali metal hydrides, HA, dihalogens, X2, and hydrogen halides, HX (A= Li, Na, K, Rb, Cs, Fr, and X = F, Cl, Br, I, At), using a range of basis sets both for DFT and CCSD methods. It has been shown that topological analysis of ELF enriches understanding of the nature of chemical bonding by enabling verification of classical concepts and provides strong evidence of new types of bonding with a mechanism of fluctuating electron density.