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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Theoretical Study on Reactions of Alkylperoxy Radicals
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Theoretical Study on Reactions of Alkylperoxy Radicals

机译：烷基氧基基团反应的理论研究

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We carried out a theoretical study on geometries, relative energies of stationary points, and reaction rate constants for ethyl + O-2, propyl + O-2, and butyl + O-2 reactions, which are important reactions in the low-temperature oxidation of corresponding alkanes. Geometries with CCSD(T)/aug-cc-pVTZ for the ethyl + O-2 system are adopted as the benchmark to choose a proper exchange-correlation functional for geometry optimization. Our results show that B3LYP with 6311+G(d,p) can provide reliable structures for this system, and structures of the other two systems are determined with this functional. The performances of the explicitly correlated CCSD(T)-F12a and the locally correlated DLPNO-CCSD(T) methods on barrier heights and reaction energies are evaluated by comparing their results with those of CCSD(T)/aug-cc-pVQZ for the ethyl + O-2 system. Our results indicate that reliable energy differences for this system are achieved with CCSD(T)-F12a using the cc-pVDZ-F12 basis set, and this method is employed in calculating single-point energies for the other two systems. The single-reference equation-of motion spin-flip coupled-cluster method is adopted to obtain the potential energy surface of the barrierless reaction C2H5. + O-2 -> CH3CH2OO, and the results are compared with those using broken-symmetry density functional theory and the Morse potential. Differences between energies with these methods are <1.6 kcal/mol, but the difference in the rate constants could be sizable at temperatures <500 K, and rate constants obtained in this work are reliable only for temperatures >500 K. Pressure dependent rate constants for these reactions are determined using the Rice-Ramsperger-Kassel- Marcus/Master equation method. The obtained reaction energies, barrier heights, and rate constants could be valuable for reactions between the large alkane radical and O-2, which are important in the low-temperature combustion of fuels such as kerosene and gasoline.
机译：我们对几何形状，静止点的相对能量和乙基+ O-2，丙基+ O-2和丁基+ O-2反应的反应速率常数进行了理论研究，这是低温氧化中的重要反应相应的烷烃。使用CCSD（T）/ AUG-CC-CC-PVTZ的几何形状被采用为基准，为几何优化选择适当的交换相关功能。我们的结果表明，具有6311 + G（D，P）的B3LYP可以为该系统提供可靠的结构，并且通过该功能确定其他两个系统的结构。通过将它们的结果与CCSD（T）/ AUG-CC-PVQZ的结果进行比较，评估明确相关的CCSD（T）-F12A和局部相关的DLPNO-CCSD（T）方法的显式相关的CCSD（T）-F12A和局部相关的DLPNO-CCSD（T）方法。乙基+ O-2系统。我们的结果表明，使用CC-PVDZ-F12基础集，使用CCSD（T）-F12A实现该系统的可靠能量差异，并且该方法用于计算其他两个系统的单点能量。采用单引用运动旋转旋转耦合簇法，得到阻挡反应C2H5的电位能表面。 + O-2 - > CH3CH2OO，并将结果与​​使用破裂对称密度函数理论和摩尔斯潜力进行比较。这些方法的能量之间的差异是<1.6千卡/摩尔，但速率常数的差异可以在温度<500k的温度<500k，并且在该工作中获得的速率常数仅适用于温度> 500k.压力依赖性速率常数这些反应使用稻米 - ramsperger-kassel-marcus / master等式方法测定。得到的反应能量，阻挡高度和速率常数对于大烷烃基团和O-2之间的反应可能是有价值的，这在诸如煤油和汽油的低温燃烧中是重要的。

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