Three-Body Noncovalent Interactions: Insights from Energy Decomposition and their influence on Halogen Bonding

Abstract

Accurate models are crucial to predict noncovalent interactions, which govern complex struc- ture, energetics, material self-assembly and reaction dynamics in complex environments. While there exist ample datasets of accurate interaction energies for bimolecular complexes, benchmark data for nonadditive three-body interactions are quite scarce, limiting the development and valida- tion of methods that capture many-body contributions. This work introduces two datasets to study two and three−body noncovalent interactions in heteromolecular trimers. The 3BHET benchmark dataset comprises 20 equilibrium noncovalent interaction energies for a small but diverse selec- tion of 10 heteromolecular trimers that combine different interactions including π − π, anion−π, cation−π and various motifs of hydrogen and halogen bonding. The 3BXB datastet in contrast, features a diverse selection of 107 heteromolecular trimers in 214 structures formed by augmenting halogen−bonded dimers with either methane or water. It presents complexes that model σ − hole interactions within each trimer, focusing on the magnitude and influence of three-body effects on the halogen bonds. Both datasets are constructed using the same level of theory and subjected to the same analysis process. The benchmark interaction energies were computed using the com- posite CCSD(T)/CBS method and a detailed energy decomposition of the two- and three-body interaction energies performed using various flavors and variants symmetry-adapted perturbation theory (SAPT). Additionally, we develop a six-dimensional potential energy surface (6D PES) for the OH-H2 system using RCCSD(T) and CCSDT corrections for the symmetric geometires and MRCI-F12 for asymmetric configurations. This PES allows for the quantum scattering calcula- tions for the computation of elastic and inelastic cross-sections.