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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Analytical Potential Energy Surface Describing Abstraction Reactions in Asymmetrically substituted Polyatomic Systems of Type CX_3Y+A- Products
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Analytical Potential Energy Surface Describing Abstraction Reactions in Asymmetrically substituted Polyatomic Systems of Type CX_3Y+A- Products

机译：CX_3Y + A-型不对称取代多原子体系中描述抽象反应的势能面

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The gas-phase reaction between chloromethane and hydrogen proceeds by two channels,Cl- and H-abstraction,and was chosen as a model of asymmetrically substituted polyatomic reactions of type CX_3Y+A ->products.The analytical potential energy surface for this reaction was constructed with suitable functional forms to represent vibrational modes,and both channels were independently fitted to reproduce experimental and theoretical information only at the stationary points.The rate constants for the Cl- and H-channels and the overall reaction were calculated using variational transition-state theory with multidimensional tunneling effect over a wide temperature range,298-3000 K.The Cl-abstraction reaction is preferred until 2100 K,while above this temperature the H-abstraction channel is favored.The theoretical overall rate constants agree with the experimental data in the common temperature range,500-800 K,with a small curvature of the Arrhenius plot due mainly to the role of the tunneling in the H-abstraction channel.This surface was then used to analyze dynamical features,such as reaction-path curvature,and coupling between the reaction-coordinate and vibrational modes.It was found qualitatively that excitation of the C-Cl and C-H stretching reactive modes enhances the forward rate constants for the Cl- and H-abstraction channels,respectively,and only the Cl-H and H-H stretching modes in the products of the Cl- and H-abstraction reactions,respectively,appear vibrationally excited.
机译：氯甲烷和氢气之间的气相反应通过Cl和H的两个吸收通道进行，并被选作CX_3Y + A->产物类型的不对称取代多原子反应的模型。该反应的分析势能面为构造具有合适的函数形式来表示振动模式，并且两个通道都独立安装以仅在固定点上重现实验和理论信息.Cl和H通道的速率常数以及整体反应是使用变迁过渡态计算的在298-3000 K的宽温度范围内具有多维隧穿效应的理论。Cl吸收反应直到2100 K才是优选的，而在此温度以上，H吸收通道是有利的。理论总速率常数与实验数据相符。常见温度范围为500-800 K，Arrhenius图的曲率较小，这主要是由于隧穿的作用然后在H吸收通道中使用该表面分析动力学特性，例如反应路径曲率以及反应坐标与振动模式之间的耦合。定性地发现C-Cl和CH拉伸反应的激发模态分别提高了Cl和H吸收通道的前向速率常数，并且在Cl和H吸收反应的产物中，只有Cl-H和HH拉伸模式分别出现了振动激发。

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