计算双分子反应速率与温度关系的量子效应的一种简单方法：在$CH_4 + H \to CH_3 + H_2$中的应用
A Simple Method for Calculating Quantum Effects on the Temperature Dependence of Bimolecular Reaction Rates: An Application to $CH_4 + H \to CH_3 + H_2$
David Z. Goodson, Dustin W. Roelse, Wan-Ting Chiang, Steven M. Valone, J. D. Doll
备注：
Submitted to Journal of the American Chemical Society, 13 pages, REVTeX, 5 figures
The temperature dependence of the rate of the reaction CH_4+H \to CH_3+H_2 is studied using classical collision theory with a temperature-dependent effective potential derived from a path integral analysis. Analytical expressions are obtained for the effective potential and for the rate constant. The rate constant expressions use a temperature-dependent activation energy. They give better agreement with the available experimental results than do previous empirical fits. Since all but one of the parameters in the present expressions are obtained from theory, rather than by fitting to experimental reaction rates, the expressions can be expected to be more dependable than purely empirical expressions at temperatures above 2000 K or below 350 K, where experimental results are not available.
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Belgian Institute for Space Aeronomy (BIRA-IASB)（比利时空间气旋研究所）；Department of Chemistry, KU Leuven（荷语鲁汶大学化学系）
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报道了低温和超低温下Li+HF（v=0，1，j=0）-->H+LiF（v '，j'）双分子散射过程的量子力学计算。利用最近得到的高精度X2 A '电子基态势能面，对总角动量为零的情况进行了计算.对于Li+HF（v=0，j=0），反应主要是由于Li原子的亚稳态的衰变而引起的共振。F-H范德华复合体。通过计算准束缚态的本征能来分配这些共振。我们还发现，虽然化学反应性大大提高了振动激发的共振得到大部分清洗振动激发HF与Li原子的反应。此外，我们发现，在低能量下，由于形成了相当深的束缚范德华络合物和相对较重的氟原子的隧穿效率较低，反应被显着抑制。
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The hydrogen abstraction reaction between H and H$_2$S, yielding HS and H$_2$ as products, has been studied within the framework of interstellar surface chemistry. High-temperature rate constants up to 2000 K are calculated in the gas phase and are in agreement with previously reported values. Subsequently low-temperature rate constants down to 55 K are presented for the first time that are of interest to astrochemistry, i.e., covering both bimolecular and unimolecular reaction mechanisms. For this, a so-called implicit surface model is used. Strictly speaking, this is a structural gas-phase m…
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Ultracold molecules offer remarkable opportunities to study chemical reactions at nearly zero temperature. Although significant progresses have been achieved in exploring ultracold bimolecular reactions, the investigations are usually limited to measurements of the overall loss rates of the reactants. Detection of the reaction products will shed new light on understanding the reaction mechanism and provide a unique opportunity to study the state-to-state reaction dynamics. Here we report on the direct observation of an exoergic atom-exchange reaction in an ultracold atom-dimer mixture. Both th…
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A mathematical model to describe the emulsion polymerization kinetics of co- and ter-polymerizations is developed. The model is based on the classical Smith-Ewart (SE) equations, within the pseudo-homopolymerization approach, with state-of-the-art models for radical entry and desorption. For co- and ter-polymerizations there are unknown parameters in the model which are related to monomer-specific gel-effect coefficients, that are needed to compute the bimolecular termination reaction rates. The unknown parameters are determined through extensive calibration of the model on literature data for…
Quantum field theory approach for multistage chemical kinetics in liquids
Voevodsky Institute of Chemical Kinetics and Combustion（Voevodsky化学动力学与燃烧研究所）；Rice University（莱斯大学）；Research Complex at Harwell, Scientific Computing, Science and Technology Facilities Council（哈韦尔研究中心，科学计算，科学与技术设施委员会）
Experimental studies of the oxygen reduction reaction (ORR) at nitrogen doped graphene electrodes have reported a remarkably low overpotential, on the order of 0.5 V, similar to Pt based electrodes. Theoretical calculations using density functional theory have lent support for this claim. However, other measurements have indicated that transition metal impurities are actually responsible for the ORR activity, thereby raising questions about the reliability of both the experiments and the calculations. In order to assess the accuracy of the theoretical calculations, various generalized gradient…
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