HNCS与H反应机理及动力学的理论研究

Theoretical Study on the Mechanisms and Kinetics of the Reaction of HNCS with H

用MP2/6-311＋＋G（d,p）和QCISD（T）/6-311＋＋G（d,p）方法研究了HNCS与H原子反应的微观机理.应用正则变分过渡态理论并结合小曲率隧道效应,计算了200-2500 K温度范围内主反应通道的速率常数,结果表明异硫氰酸（HNCS）与H的反应为多通道、多步骤的复杂反应,找到4个可能的反应通道,生成产物H2NCS的通道为主反应通道.反应速率常数随温度升高而增大,在整个温度范围内变分效应对速率常数计算影响较大,而隧道效应在低温区对反应速率的影响较显著.

The reaction mechanism of HNCS with H has been investigated by using MP2 method with 6-311 ＋＋ G （d,p） basis set. The single point energies of the species have been corrected at the QCISD（T）/ 6-311 ＋＋ G（d,p） level. The rate constants have been calculated over the temperature range of 200-2 500 K by using variational transition state theory and the small-curvature tunneling has been included. The results show that four reaction channels have been identified and H2NCS is the main product. It is found that the rate constants of the main reaction channel are positively dependent on the temperature. The variational effect on the calculation of rate constants is very obvious over the whole temperature range and the small-curvature tunnelling effect is very important in the lower temperature range.