Revealing strong interactions with the reduced density gradient: a benchmark for covalent, ionic and charge-shift bonds

Abstract : The visualization of covalent interactions has been a common practice in theoretical chemistry thanks to the Electron Localization Function (ELF). More recently , the reduced density gradient (RDG) has been introduced as a tool for revealing non-covalent interactions. Along reactions interactions change from weak to strong and vice versa. Thus, a tool enabling to analyze all of them simultaneously is fundamental for reactivity studies. This contribution is aimed at filling this gap within the NCI approach. We will highlight the ability of RDG to reveal also strong interactions and produce a benchmark that covers covalent, ionic and charge-shift bonds. The ability of the NCI descriptor to differentiate among them will be highlighted.