Direct ab initio dynamics calculations of thermal rate constants for the CH4 + O2 = CH3 + HO2 reaction
Direct ab initio dynamics calculations of thermal rate constants for the CH4 + O2 = CH3 + HO2 reaction
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DOI：
10.1007/s11224-014-0426-2
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发表时间：
2014-10-01
影响因子：
1.7
通讯作者：
Ratkiewicz, Artur
中科院分区：
文献类型：
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作者：
Mai, Tam V-T.;Duong, Minh V.;Ratkiewicz, Artur
利用传统的过渡态理论（TST）和典型变分TST方法从第一原理出发计算了CH4 + O-2 = CH3 + HO2反应的热速率常数，并对显式阻碍旋转处理进行了修正。采用CCSD(T)/aug-cc-pVTZ//BH&HLYP/aug-cc-pVDZ方法沿最小能量路径表征必要势能面。我们发现，阻碍旋转处理的校正以及再交叉效应显著影响标题过程的速率常数。在300- 2500 K的温度范围内，计算出的正反方向的速率常数用修正的Arrhenius形式表示为和(cm（3)分子（-1）s(-1)）。结果与文献数据吻合较好，为研究全烷烃+ O-2 =烷基自由基+ HO2反应类提供了坚实的基础信息。
Thermal rate constants of the CH4 + O-2 = CH3 + HO2 reaction were calculated from first principles using both the conventional transition state theory (TST) and canonical variational TST methods with correction from the explicit hindered rotation treatment. The CCSD(T)/aug-cc-pVTZ//BH&HLYP/aug-cc-pVDZ method was used to characterize the necessary potential energy surface along the minimum energy path. We found that the correction for hindered rotation treatment, as well as the re-crossing effects noticeably affect the rate constants of the title process. The calculated rate constants for both forward and reverse directions are expressed in the modified Arrhenius form as and (cm(3) molecule(-1) s(-1)) for the temperature range of 300-2,500 K. Being in good agreement with literature data, the results provide solid basis information for the investigation of the entire alkane + O-2 = alkyl radical + HO2 reaction class.