HNCO与NO自由基反应机理的从头算研究

采用HF从头算法,在6-31G基组水平上系统研究了HNCO与NO自由基的反应机理.全参数优化了反应过渡态、中间体的几何构型,并通过振动分析对过渡态结构进行了确认,然后依据内禀反应坐标(IRC)理论,计算分析了反应途径上分子结构的变化过程;采用全电子的QCISD(T)方法对各驻点进行了单点能量校正,得出各步反应的反应位垒和反应热。结果表明,HNCO与NO自由基的反应有3种通道,通道1生成产物HNNO和CO,通道2生成产物HNN和CO_2,通道3生成产物HN和NCO_2,通过对反应位垒和反应热的比较,得出反应通道3为主反应通道。

Computational study on the reaction mechanism of HNCO with NO

Using HF method,the reaction mechanisms of HNCO with NO were systematically studied.The geometries of the transition states,the intermediates were completely optimized, every transition state was confirmed by the numbers of virtual frequency.The changing of main bond lengths as a function of reaction coordinates were studied by the intrinsic reaction coordinate(IRC) paths.The energies of all species were further calculated using QCISD method.The results showed that the reaction HNCO+NO involves three channels.By the energy barriers and thermodynamic quantities comparison,the third channel in which the HN and NCO_2 were produced was the dominant one.