Unveiling the energetic complexity of noncovalent interactions in halogenated dimers

The understanding of noncovalent interactions is crucial in explaining critical phenomena such as self-assembly, chemical reactivity, and crystallization. This work examines the energetic diversity of conformations and local minima for several halogenated dimers, represented as R-X (R = H, F, CH₃, CF₃; X = Cl, Br, I). Thousands of configurations are randomly generated and refined through geometric optimizations to yield a diverse set of molecular conformers. Frequency calculations were performed for all optimized conformers to confirm that they are local minima. The noncovalent interactions in optimized dimers of halogen-containing molecules were analyzed with atom in molecules (AIM) method and symmetry-adapted perturbation theory (SAPT). Additionally, a protocol for generating machine learning models to recover accurate predictions of the physically meaningful SAPT energy components with minor computational cost is presented. These results deepen our understanding of the intricate energy balance and dedicated equilibrium of different noncovalent interactions in halogenated dimers.