Kinetics and mechanism of O (3P) reaction with CH3CHF2: a theoretical study
Kinetics and mechanism of O (3P) reaction with CH3CHF2: a theoretical study
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DOI：
10.1021/jp036446u
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发表时间：
2004-01
影响因子：
2.9
通讯作者：
Qingzhu Zhang;†. A. R. Q. Zhang;Y. Gu
中科院分区：
文献类型：
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作者：
Qingzhu Zhang;†. A. R. Q. Zhang;Y. Gu
首次用从头算直接动力学方法对O（3 P）与CH 3CHF 2反应进行了理论研究。该反应通过两种可能的途径进行：从甲基（CH 3）中提取H和从次甲基（CH）中提取H。在每个夺氢通道上都找到了3A“和3A”对称性的两个近简并鞍点。在QCISD（T）/ 6-311+G（3df，2 p）//MP2/6- 311 G（d，p）水平上，从CH 3基团上抽氢的势垒比从CH基团上抽氢的势垒高约5 kcal/mol.讨论和比较了所有通道的几何形状、广义简正振动频率和沿着反应路径的势能的变化。在从头算数据的基础上，采用正则变分过渡态理论（CVT）和小曲率隧穿（SCT）修正方法，在200 ~ 3000 K的宽温度范围内，计算了各通道的速率常数.理论R…
The reaction of atomic O (3P) with CH3CHF2 has been studied theoretically using ab initio direct dynamics methods for the first time. This reaction takes place through two possible channels: H abstraction from the methyl group (CH3) and H abstraction from the methyne group (CH). Two nearly degenerate saddle points of 3A‘ ‘ and 3A‘ symmetries have been located for each hydrogen abstraction channel. At the QCISD(T)/ 6-311+G(3df,2p)//MP2/6-311G(d,p) level, the potential barrier of H abstraction from the CH3 group is about 5 kcal/mol higher than that of H abstraction from the CH group. Changes of geometries, generalized normal-mode vibrational frequencies, and potential energies along the reaction paths for all the channels are discussed and compared. On the basis of the ab initio data, the rate constants of each channel have been deduced by canonical variational transition-state theory (CVT) with small-curvature tunneling (SCT) correction method over a wide temperature range of 200∼3000 K. The theoretical r...