HCO自由基与NO_2反应机理的理论研究

Theoretical Study on Mechanism of the Reaction between HCO Radical and NO_2

用密度泛函理论(DFT)的B3LYP和B3P86方法,在6 311++G(d,p)基组水平上研究了HCO自由基与NO2反应的微观机理,全参数优化了反应过程中各反应物、中间体、过渡态和产物的几何构型.在CBS QB3及G3水平上计算了各驻点的能量.振动分析和IRC计算结果都证实了中间体和过渡态的真实性.从对HCO自由基与NO2的反应机理的研究结果看,HCO自由基与NO2反应的几条通道控制步骤的活化能分别为112.49和291.49kJ·mol-1,反应HCO+NO2→HONO+CO的活化能较低为主反应通道.理论计算所得的反应产物是HONO,CO2,NO,CO,H,这些产物已被实验手段检测到,这说明以上结论与实验值相吻合,从而证明我们的研究结果是可靠的.

Density function theory is performed to study the mechanism of the reaction of HCO radical with NO_2. The geometric configurations of reactants, intermediates, transition states and products are optimized by B3LYP,B3P86 methods at 6-311++G(d,p) level. The energies of stationary points along the pathways are calculated at CBS-QB3 and G3 levels. Intermediates and transition states are confirmed by the results of vibration analysis and IRC calculation. From the research on the mechanism of the reaction between HCO radical and NO_2, one can see that the reaction has several pathways and many steps, and activation energies of these pathways' control steps are 112.49 and 291.49 kJ·mol^(-1), respectively. Relatively, the pathway: HCO+NO_2→CO+HONO has the smallest activation energy, which is the main reaction pathway. The study shows that the main products are HONO,CO_2,NO,CO,H. These products have been detected by experiments, which proves that our results are believable.