Evaluation of DFT methods to study reactions of benzene with OH radical

摘要

Several density functional theory" (DFT) methods are applied to two different reaction channels involving OH ? + C _6H _6, and the results compared with high-level ab initio calculations. The OH ? adds directly to one C atom in the first channel, first forming an encounter complex with the OH ? poised above the aromatic plane. B3LYP, BH&HLYP, and MPW1K compute an accurate estimate of the overall exothermicity, whereas M05-2X, PBE0, and PBEPBE overestimate this quantity to some degree. With the exceptions of PBEPBE and PBE0, the other methods produce an acceptable barrier to addition. All approaches except BH&HLYP correctly predict an exothermic H ? abstraction, although PBEPBE is too exothermic. The BH&HLYP barrier to H ? abstraction is too high while the MPW1K, PBE0, and B3LYP values are better, and M05-2X the best.