采用密度泛函理论BB1K/6-31+G(d,p)计算了反应CF3CH2CH3+OH各反应通道上驻点的稳定结构和振动频率,并分别在BMC-CCSD,MC-QCISD和G3(MP2)水平上进行了单点能校正.运用变分过渡态理论,在BMC-CCSD//BB1K,MC-QCISD//BB1K,G3(MP2)//BB1K以及BB1K水平上计算了各反应通道的速率常数,讨论了—CH2和—CH3基团上H提取通道对总反应的贡献,并与已有实验和理论结果进行了对比.计算结果表明,BMC-CCSD水平上的速率常数与实验测量值符合得很好,进而给出了该水平上反应在200~1000K温度范围内速率常数k(cm3.molecule-1.s-1)的三参数表达式:k=1.90×10-21T3.21exp(-292.62/T).
The optimized geometries and frequencies of all the stationary points involved in each reaction channel of the CF3CH2CH3+OH reaction were calculated at the BB1K/6-31+G(d,p) level,and the potential energy profile is further refined by single-point energy calculations at the BMC-CCSD,MC-QCISD and G3(MP2) levels.The rate constants of all channels were evaluated by variational transition state theory(VTST) at the BMC-CCSD//BB1K,MC-QCISD//BB1K,G3(MP2)//BB1K and BB1K levels over a wide temperature range of 2001000 K,and the contribution of H-abstraction from the CH2 and CH3 groups to the total reaction was discussed.The present calculations show that the rate constants evaluated at the BMC-CCSD//BB1K level are in excellent agreement with the available experimental values in the measured temperature range.Finally,the three-parameter rate-temperature expression of the total reaction over the whole temperature range 2001000 K was given as k=1.90×10-21T 3.21exp(-292.62/T).