论文部分内容阅读
为了弄清CHF与O_2反应在单重态势能面(PES)上的机理,我们在B3LYP/6-311++G(d,p)水平上对该反应作了详细的理论研究。优化了反应势能面上的反应物、中间体、过渡态和产物的几何构型,并在相同水平上用内禀反应坐标法确认了中间体和过渡态之间的相关性。为了获得准确的能量,我们将B3LYP/6-311++G(d,p)方法优化得的各驻点几何构型用QCISD/6-311++G(d,p)作了单点能计算。研究发现CHF+O_2反应,第一步经无势垒络合生成HFCOO,然后经过一系列的异构化和断键过程,生成P_1(HCO+FO)、P_2(HF+CO_2)和P_3(CO+HOF)。其中P_1(HCO+FO)通道最缺乏竞争力,而P_2(HF+CO_2)通道最有优势。在产物P_2和P_3的生成路径中,所有的过渡态能量都低于反应物,因而该反应在低温中起着重要作用。
In order to clarify the mechanism of the CHF reaction with O 2 on the singlet potential energy surface (PES), we made a detailed theoretical study of the reaction at the B3LYP / 6-311 ++ G (d, p) level. The geometries of reactants, intermediates, transition states and products on the reaction potential surface were optimized, and the correlation between intermediates and transition states was confirmed by the intrinsic reaction coordinate method on the same level. In order to get accurate energy, we use QCISD / 6-311 ++ G (d, p) to make a single point energy for each stagnation point geometry optimized by B3LYP / 6-311 ++ G (d, p) Calculate. It was found that CHF + O 2 reacted in the first step via barrier-free barrier to form HFCOO and then formed a series of isomerization and bond breaking processes to generate P 1 (HCO + FO), P 2 (HF + CO 2) and P 3 + HOF). Among them, P 1 (HCO + FO) channel was the least competitive, while P 2 (HF + CO 2) channel had the most advantage. In the production path of the products P_2 and P_3, all of the transition state energies are lower than the reactants, and the reaction plays an important role in the low temperature.