Theoretical Investigation on Water-Free, Water- and Self-Assisted H-Abstraction Reactions from Dimethylamine by Hydroxy Radicals

Accurate branching ratios of the H-abstraction reactions from dimethylamine (DMA) by OH radicals are important in understanding the atmospheric fate of DMA. In this work, the reaction kinetics of the water-free, water-assisted, and self-assisted H-abstraction reactions between DMA and OH radicals are accurately determined using the multipath canonical variational theory with the small-curvature tunneling correction, to explore the catalytic effects of the reactant (DMA) and product (water). To choose a suitable method that well describes the current reaction systems, various combinations with seven DFT methods and six basis sets are first evaluated, and the M08-HX/ma-TZVP method is identified as the most appropriate, with a mean unsigned deviation of 0.9 kcal mol