理论研究OCS与CN自由基的反应机理

氧硫化碳(OCS)是大气中含量丰富的含硫气体，也是唯一一种能通过扩散进入平流层的含硫物种. 采用高水平分子轨道理论方法研究了OCS与CN自由基在2A′势能面上的反应机理. 在B3LYP/6-31G(2df)水平下优化了反应物、中间体、过渡态及产物的构型参数，并进行了振动频率分析. 单点能计算采用QCISD(T)/-311+G(3df)理论水平. 在QCISD(T)/6-311+G(3df)//B3LYP/6-31G(2df)水平下构筑了反应的势能剖面. 计算结果表明：在通常的大气条件下，NCS和CO是主要反应产物. 然而，随着温度的升高，生成CNS和CO的反应通道可能变成竞争反应通道.

Theoretical study on the mechanism for the reaction of OCS and CN redicals

Carbonyl sulfide(OCS) is known to be an important atmospheric species The microcosmic mechanism for the reaction of OCS with CN radicals is studied by using high level molecular orbital theory Geometries of the reactants,intermediates,transi-tion states,and products are optimized at the B3LYP level with the 6-31G(2df) basis set The single-point energy calculations are carried out at the QCISD(T)/6-311+G(3df) level The profile of the potential energy surface is constructed The result shows that the NCS and CO product channel dominates this reaction under general atmospheric conditions.However,the forming of CNS and CO products may become a competitive channel with a temperature increase,especially at the combustion process of sulfur-con-taining systems.