中文摘要：

在G3B3,CCSD（T）/6-311＋＋G（d,p）//B3LYP/6-311＋＋G（d,p）水平上详细研究了CH3SH与基态NO2的微观反应机理.在B3LYP/6-311＋＋G（d,p）水平得到了反应势能面上所有反应物、过渡态和产物的优化构型,通过振动频率分析和内禀反应坐标（IRC）跟踪验证了过渡态与反应物和产物的连接关系.在CCSD（T）/6-311＋＋G（d,p）和G3B3水平计算了各物种的能量,得到了反应势能面.利用经典过渡态理论（TST）与变分过渡态理论（CVT）并结合小曲率隧道效应模型（SCT）,分别计算了在200～3000K温度范围内的速率常数k^TST,k^CVT和k^CVT/SCT.研究结果表明,该反应体系共存在5个反应通道,其中N进攻巯基上H原子生成CH3S＋HNO2的通道活化势垒较低,为主要反应通道.动力学数据也表明,该通道在200～3000K计算温度范围内占绝对优势,拟合得到的速率常数表达式为k1^CVT/SCT=1.93×10^-16T^0.21exp（-558.2/T）cm^3·molecule^-1·s^-1.

英文摘要：

The reaction mechanism of CH3SH with NO2 was investigated by using the density functional theory. The optimum geometries and frequencies of the reactants, transition states and products were computed at the B3LYP/6-311 ＋＋G（d,p） level of theory. Stationary points of the reaction channels were confirmed by the vibration analysis and the intrinsic reaction coordinate （IRC） tracing. The species energies at all stationary points were corrected by single-point calculations at the G3B3 and CCSD（T）/6-311 ＋ ＋G（d,p） levels. The rate constants of the reactions were evaluated by means of the classical transition state theory and the canonical variational transition state theory in which the small-curvature tunneling correction was included. Five possible reaction channels have been identified for the title reaction. Based on the potential energy surface and the kinetics, it can be concluded that the major reaction channel is the hydrogen abstraction of SH by N atom of NO2, leading to the formation of CH3S and HNO2. In the temperature range of 200- 3000 K, the overall rate constants are of positive temperature dependence, and the rate constant of channel R→TS1→P1 can be described by the expression as kl^CVT/SCT= 1.93 × 10^-16T^0.21exp（-558.2/T） cm^3omolecule^-1·s^-1.