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Ab initio study on the reaction mechanism of ozone with the chlorine atom

机译：从头开始研究臭氧与氯原子的反应机理

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Ab initio calculations of the potential energy surface for the Cl+O-3 reaction have been performed using the MP2, QCISD(T), CCSD(T), G2, G2M, CASPT2, and MRCI methods with various basis sets. The results show that the reaction pathway can be divided in two parts. The reaction starts on the nonplanar pathway when the Cl atom attacks a terminal oxygen of ozone via TS1, producing a virtual intermediate, a nonplanar chlorine trioxide B. B isomerizes to another virtual intermediate, planar C, which immediately dissociates to ClO+O-2 in the coplanar manner. The ClOOO intermediates B and C disappear at the QCISD level of theory. The calculations confirm the direct reaction mechanism for Cl+O-3 but the existence of a very flat plateau on the potential energy surface in the region of B, TS2, C, and TS3 can have some effect on the reaction dynamics. TS1 is the critical transition state determining the rate of the Cl+O-3 reaction. High level calculations, such as QCISD(T), CCSD(T), MRCI, and CASPT2 with the basis sets from moderate to very large, at the QCISD and CASSCF optimized geometry of TS1, consistently predict the barrier to be about 4-5 kcal/mol, much higher than the experimental value (below 1 kcal/mol). New experimental measurements as well as even higher level theoretical calculations are encouraged in order to resolve this discrepancy. (C) 1998 American Institute of Physics. [S0021-9606(98)02948-1]. [References: 40]
机译：使用MP2，QCISD（T），CCSD（T），G2，G2M，CASPT2和MRCI方法以及各种基础集对Cl + O-3反应的势能面进行了从头算计算。结果表明，反应途径可分为两部分。当Cl原子通过TS1攻击臭氧的末端氧时，反应在非平面途径上开始，产生一个虚拟中间体非平面三氧化氯B。B异构化为另一个虚拟中间体平面C，该中间体立即解离为ClO + O-2以共面的方式。 C10OO中间体B和C在理论的QCISD水平上消失。计算证实了Cl + O-3的直接反应机理，但在B，TS2，C和TS3区域的势能表面上存在一个非常平坦的平台，会对反应动力学产生一定影响。 TS1是决定Cl + O-3反应速率的临界过渡态。在TS1的QCISD和CASSCF优化几何条件下，从中等到非常大的基集的高级别计算（例如QCISD（T），CCSD（T），MRCI和CASPT2）一致预测障碍约为4-5 kcal / mol，远高于实验值（低于1 kcal / mol）。鼓励采用新的实验方法以及更高水平的理论计算来解决这一差异。 （C）1998美国物理研究所。 [S0021-9606（98）02948-1]。 [参考：40]

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