Potential Energy Surface for Asymmetrically Substituted Reactions of Type CWXYZ + A. Kinetics Study
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- 作者：Cipriano Rangel ; Joaquí ; n Espinosa-Garcí ; a
- 刊名：Journal of Physical Chemistry A
- 出版年：2007
- 出版时间：June 14, 2007
- 年：2007
- 卷：111
- 期：23
- 页码：5057 - 5062
- 全文大小：69K
- 年卷期：v.111,no.23(June 14, 2007)
- ISSN：1520-5215
文摘
The CHClF2 + Cl 
ClH + CClF2 gas-phase abstraction reaction was chosen as a model of asymmetricallysubstituted polyatomic reactions of type CWXYZ + A products. The analytical potential energy surface forthis reaction was constructed with suitable functional forms to represent vibrational modes, and calibratedwith respect to experimental thermal rate constants which are available over the temperature range 296-410 K. On this surface, the thermal rate constants were calculated using variational transition-state theorywith semiclassical transmission coefficients over a wider temperature range, 200-2500 K, therefore obtainingkinetics information at lower and higher temperatures than are experimentally available. This surface wasalso used to analyze dynamical features, such as tunneling and reaction-path curvature. In the former, theinfluence of the tunneling factor was important since a light hydrogen atom passes through the barrier. In thelatter, it was found that vibrational excitation of the C-F and C-Cl stretching modes can be expected in theexit channel.
ClH + CClF2 gas-phase abstraction reaction was chosen as a model of asymmetricallysubstituted polyatomic reactions of type CWXYZ + A products. The analytical potential energy surface forthis reaction was constructed with suitable functional forms to represent vibrational modes, and calibratedwith respect to experimental thermal rate constants which are available over the temperature range 296-410 K. On this surface, the thermal rate constants were calculated using variational transition-state theorywith semiclassical transmission coefficients over a wider temperature range, 200-2500 K, therefore obtainingkinetics information at lower and higher temperatures than are experimentally available. This surface wasalso used to analyze dynamical features, such as tunneling and reaction-path curvature. In the former, theinfluence of the tunneling factor was important since a light hydrogen atom passes through the barrier. In thelatter, it was found that vibrational excitation of the C-F and C-Cl stretching modes can be expected in theexit channel.