论文部分内容阅读
采用量子化学QCISD(T)/6-311++G(d,p)//B3LYP/6-311+G(d,p)方法研究了H2FCS单分子分解反应的微观动力学性质,构建了反应势能剖面.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kTST,kCVT和kCVT/SCT.计算结果表明,H2FCS可经过不同的反应通道生成10种小分子产物,脱H反应和HF消去反应为标题反应的主反应通道,其中HF消去反应产物HCS可由两条反应通道生成.在200～3000K温度区间内得到三条反应通道的表观反应速率常数三参数表达式分别为kPath(1)CVT/SCT=3.6×10-41T12.8exp(11597.7/T)cm3·molecule-1·s-1,kPCaVthT(3/S)CT=3.6×10-15T5.52exp(19769.4/T)cm3?molecule-1·s-1和Path(4)CVT/SCT=1.5×10-3T2.03exp(21821.6/T)cm3·molecule-1·s-1.速率常数计算结果显示,量子力学隧道效应在低温区间对反应速率常数的影响显著,而变分效应在计算温度范围内可以忽略.
The microkinetic properties of H2FCS mononuclear decomposition were investigated by quantum chemistry QCISD (T) / 6-311 ++ G (d, p) / B3LYP / 6-311 + G (d, p) Potential section of potential energy kTST, kCVT and kCVT / kCVT in the temperature range from 200K to 3000K were calculated by classical transient state theory (TST) and variational transition state theory (CVT) combined with small curvature tunneling effect model (SCT) SCT. The calculated results show that H2FCS can generate 10 kinds of small molecule products through different reaction channels, and the de-H reaction and HF elimination reaction are the main reaction channels of the title reaction, in which HF elimination reaction product HCS can be generated by two reaction channels. At 200 The three-parameter expressions of the apparent reaction rate constants of the three reaction channels obtained in the temperature range of ~ 3000K are respectively kPath (1) CVT / SCT = 3.6 × 10-41T12.8exp (11597.7 / T) cm3 · molecule-1 · s- 1, kPCaVthT (3 / S) CT = 3.6 × 10-15T5.52exp (19769.4 / T) cm3 molecule-1 · s-1 and Path (4) CVT / SCT = 1.5 × 10-3T2.03exp (21821.6 / T) cm3 · molecule-1 · s-1. The calculated results of the rate constants show that the tunneling effect of quantum mechanics has a significant effect on the reaction rate constant in the low temperature range, while the variational effect can be neglected within the calculated temperature range .