On the theoretical rationalization of intermolecular interactions: insights from DFT energy partitioning schemes

Abstract

The energy partitioning schemes are powerful tools bridging the gap between elementary quantum chemistry and conceptually interpretation of interactions. In this work, the density functional theory (DFT)-based energy partitioning schemes through conventional and modern formalisms have been utilized to find out what energetic components govern the nature and origin of different types of intermolecular interactions. To this end, diverse datasets covering wide ranges of interactions at equilibrium geometries as well as during the potential energy curves are investigated. With more or less different roles on the stabilization and destabilization, the electrostatic, exchange–correlation, and steric effects are shown to be the dominant factors contributing to the total interaction energies. Furthermore, the energy decomposition analyses have also been employed during the potential energy curve of the systems under study. The obtained profiles of the energetic components and their changing pattern ascertain that exchange–correlation effects alongside electrostatic and noninteracting kinetic energy components are determinant contributions following the variation trend of interaction energies. On the other hand, we find that for both equilibrium and nonequlibrium geometries of the formed complexes in each category there are reasonable and meaningful correlations between interaction energies and any of their components as well as energy components themselves based on one- to three-variables fittings. To wrap up, our findings unveil that the traditional and novel DFT energy partitioning schemes can pave the way to figure out the essence of intermolecular interactions, where the DFT energetic components come into play and further evidences of their quality to theoretical rationalization of intermolecular interactions are showcased.