Predicting CH/π Interactions with Nonlocal Density Functional Theory

We examine the performance of a recently developed nonlocal density functional in predicting a model noncovalent interaction, namely the weak bond between an aromatic π system and an aliphatic CH group. The new functional is a significant improvement over traditional density functionals, providing results which compare favorably to high‐level quantum‐chemistry techniques, but at considerably lower computational cost. Interaction energies in several model CH/π systems are in good general agreement with coupled‐cluster calculations, though equilibrium distances are consistently overpredicted when using the revPBE functional for exchange. The new functional predicts changes in energy upon addition of halogen substituents correctly.