CH_3O_2~·+NO气相反应的密度泛函理论研究

DFT Study of Reaction CH_3O_2~·+NO→CH_3O~·+NO_2 in Gas Phase

用密度泛函方法分别研究了单态和三态 CH3 O·2 + NO CH3 O· + NO2 气相反应 .结果表明 ,反应中 NO进攻 CH3 O·2 经过了一个顺反异构化的过程 ,摘取 CH3 O·2 的端基氧 .整个反应是吸热反应 ,理论计算吸热值为 5 0 .93k J/ mol,单态为多通道多步骤反应 ,决定速度步骤的能垒为 1 90 .6 1 k J/ mol.而三态为单通道反应 ,其决定速度步骤的能垒为 1 6 3.31 k J/ mol.三态反应为最佳反应通道 .该反应的研究将为保护臭氧层及大气环境提供重要的理论依据 .

The mechanism of the reaction CH 3O · 2+NO CH 3O ·+NO 2 in gas phase has been studied by using density functional theory. The geometries of reactants, transition states, intermediates and products have been optimized by B3LYP/6-31G * and HF/6-31G * basis set. Transition states and intermediates have been verified by frequency analysis. The reaction path has been traced by Fukui′s theory of intrinsic reaction coordinate(IRC), with the change of geometry parameter being computed. In order to obtain credible energy, single points energy has been calculated by QCISD methods using the 6-311G ** basis set with zero-point energy correction done by B3LYP method. The isomerizations of the intermediates and the charge densities have been analyzed. The results show that the whole reaction comes through many courses, and it is an endothermic reaction with 50.93 kJ/mol endothermic value calculated. Among the three reaction paths proposed, the triplet state reaction is the most probable one with the lowest activation energy of 163.31 kJ/mol. This work will provide the important theoretical foundation for protecting the \{ozonosphere\} and atmosphere.