Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
J Phys Chem A. 2010 Nov 4;114(43):11477-82. doi: 10.1021/jp102947w.
The reaction of ClO with Cl and its related reverse processes have been studied theoretically by ab initio quantum chemical and statistical mechanical calculations. The geometric parameters of the reactants, products, and transition states are optimized by both UMPW1PW91 and unrestricted coupled-cluster single and double excitation (UCCSD) methods with the 6-311+G(3df) basis set. The potential energy surface has been further refined (with triple excitations, T) at the UCCSD(T)/6-311+G(3df) level of theory. The results show that Cl(2) and O ((3)P) can be produced by chlorine atom abstraction via a tight transition state, while ClOCl ((1)A(1)) and ClClO ((1)A') can be formed by barrierless association processes with exothermicities of 31.8 and 16.0 kcal/mol, respectively. In principle the O ((1)D) atom can be generated with a large endothermicity of 56.9 kcal/mol; on the other hand, its barrierless reaction with Cl(2) can readily form ClClO ((1)A'), which fragments rapidly to give ClO + Cl. The rate constants of both forward and reverse processes have been predicted at 150-2000 K by the microcanonical variational transition state theory (VTST)/Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The predicted rate constants are in good agreement with available experimental data within reported errors.
通过从头算量子化学和统计力学计算，理论上研究了 ClO 与 Cl 的反应及其相关的逆过程。采用 UMPW1PW91 和非限制耦合簇单双激发（UCCSD）方法，在 6-311+G(3df)基组上对反应物、产物和过渡态的几何参数进行了优化。在 UCCSD(T)/6-311+G(3df)理论水平上进一步细化了势能面（采用三重激发，T）。结果表明，Cl(2)和 O((3)P)可以通过氯原子的攫取通过紧过渡态生成，而 ClOCl((1)A(1))和 ClClO((1)A')可以通过无势垒的缔合过程形成，分别具有 31.8 和 16.0 kcal/mol 的放热。原则上可以用 56.9 kcal/mol 的大吸热生成 O((1)D)原子；另一方面，它与 Cl(2)的无势垒反应可以容易地形成 ClClO((1)A')，它迅速断裂生成 ClO + Cl。通过微正则变分过渡态理论(VTST)/Rice-Ramsperger-Kassel-Marcus(RRKM)理论，在 150-2000 K 预测了正向和逆向过程的速率常数。预测的速率常数与报道的误差范围内的可用实验数据吻合良好。
