Beyond Energetic and Scalar measures with Vector Fields: Next Generation QTAIM

Next Generation Quantum Theory of Atoms in Molecules (NG-QTAIM) is constructed from the eigenvectors of the Hessian of the total (real-space) charge density distribution ρ(r) field and can also use the eigenvectors of the stress tensor σ(r) and the Ehrenfest Force F(r) = -∙σ(r). 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. Molecular and solid state systems as well as surfaces may also be considered. As a consequence, NG-QTAIM can uniquely be used to investigate iso-energetic phenomena where the total reliance on differences in geometric measures, i.e. positions of nuclei, is removed. In partnership with non-ionizing ultra-fast laser irradiation, NG-QTAIM has been demonstrated as a useful tool in the emerging field of ultra-fast dynamics which will be essential for the design and control of molecular materials in external fields.

Steven R. Kirk and Samantha Jenkins, “Beyond energetic and scalar measures: Next generation quantum theory of atoms in molecules”, WiRES: Computational Molecular Science 12, 6, e1611, 2022. DOI: 10.1002/wcms.1611