Beyond energetic and scalar measures: Next generation quantum theory of atoms in molecules. (13th March 2022)

• Record Type: Journal Article
• Authors: Kirk, Steven R.; Jenkins, Samantha
• Is Part Of: Wiley interdisciplinary reviews. Volume 12:Number 6(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-13
• Subjects: Cahn–Ingold–Prelog classifications -- next generation QTAIM -- QuantVec -- stereochemistry -- symmetry breaking; Chemistry, Physical and theoretical -- Periodicals; Cheminformatics -- Periodicals; Biochemistry -- Periodicals; 541.220285
• DOI: 10.1002/wcms.1611
• Languages: English
• ISSNs: 1759-0876

Abstract

Abstract: Next generation quantum theory of atoms in molecules (NG‐QTAIM) is currently the only vector‐based quantum chemical theory as all other quantum chemical theories are scalar‐based. NG‐QTAIM can, for instance, be used to distinguish enantiomers, isotopomers undergoing normal modes of vibration, predict ring‐opening reaction products, ground and excited states at a conical intersection and predict reaction pathways of permutation‐inversion isomers. As a consequence, NG‐QTAIM can uniquely be used to investigate iso‐energetic phenomena where the reliance on differences in geometric measures is removed. NG‐QTAIM has already been used to determine molecular chirality consistent with the Cahn–Ingold–Prelog (CIP) classifications for chiral molecules in addition to the reactant and product of a chiral SN 2 reaction. The CIP classifications however, cannot quantify the chirality of intermediate reaction structures due to their formally achiral nature. We identify the presence of chirality by quantifying a helical response of the bond electrons consistent with photoexcitation circular dichroism experiments that utilize the helical motion of the bound electrons for chiral discrimination. NG‐QTAIM can also be used to provide nongeometric based reasoning as to why there are stronger hydrogen‐bonds in cyclic water clusters compared with compact water clusters. Additionally, the effects of electric‐fields and laser irradiation in conditions not amenable to explanation using scalar measures are quantified. The QuantVec software is introduced, which coordinates external programs and efficiently computes the NG‐QTAIM analyses using the wavefunctions from a wide range of ground and excited states computed with DFT, coupled‐cluster, complete active space SCF, configuration interaction, or quantum dynamics methods. This article is categorized under: Structure and Mechanism > Molecular Structures Structure and Mechanism > Reaction Mechanisms and Catalysis Software > Quantum Chemistry Abstract : We consider the consequences for computational chemistry of removing the reliance on scalar measures. The deformation anisotropy of chemical and iso‐energetic phenomena are revealed by the eigen‐properties within next generation quantum theory of atoms in molecules. The symmetry‐breaking properties required to elucidate the iso‐energetic as well as deformation anisotropy chemical phenomena are computed using Quantvec.