Influence of Small Changes in Intermolecular Distances on Results of Interaction Energy Decomposition for Stacking Interactions, Hydrogen Bonds, and Antiparallel Interactions

A SAPT (Symmetry-Adapted Perturbation Theory) decomposition analysis was performed for various types of noncovalent interactions (stacking, hydrogen bonds, and antiparallel) for various distances of interacting fragments. Although the total interaction energy does not significantly change within the small range around the optimal distance, the energy contributions can significantly change in some systems. This is particularly pronounced for stacking interactions, while for hydrogen bonds and antiparallel interactions the energy contributions do not significantly change around the optimal distance. Thus, the nature of interactions should be carefully interpreted, as small alterations in distances between the interacting fragments can sometimes lead to significant changes in energy contributions, especially for stacking interactions.