Using Energetic Information Quantities from Density Functional Theory to Simultaneously Identify Both Covalent and Noncovalent Interactions

Covalent bonding and noncovalent interactions are important chemical concepts and how to identify them has been of current interest in the literature. Within the framework of density functional theory (DFT), we recently proposed a few qualitative descriptors to categorize different types of interactions with Pauli energy and its derivatives. In this work, we expand the scope by including the quantities derived from energetic information, which were recently proposed and thoroughly investigated by us from the framework of information-theoretic approach (ITA) in DFT. To that end, six energetic information quantities stemmed from the steric energy (Es), including Shannon entropy SSEs ${S_S<^>{E_s } }$ , Fisher information IFEs ${I_F<^>{E_s } }$ , information gain IGEs ${I_G<^>{E_s } }$ , alternative Fisher information IF'Es ${I_F<^>{{<^>\prime}E_s } }$ , relative Fisher information FrIEs ${{}_F<^>r I<^>{E_s } }$ , and relative alternative Fisher information FrI'Es ${{}_F<^>r I<^>{{<^>\prime}E_s } }$ are examined for the purpose. A strong linear correlation of Es or its topological analysis results with different covalent bond orders is established. We also unveil that signature isosurfaces of different categories of interactions from IGEs ${I_G<^>{E_s } }$ and FrI'Es ${{}_F<^>r I<^>{{<^>\prime}E_s } }$ can be employed to simultaneously identify single, double, triple, and quadruple covalent bonds, ionic and metallic bonds, and van der Waals interactions. This work provides another pathway for us to use density-based quantities to simultaneously identify covalent and noncovalent interactions.