Multiconfigurational study on the synchronous mechanisms of the ClO self-reaction leading to Cl or Cl2
Multiconfigurational study on the synchronous mechanisms of the ClO self-reaction leading to Cl or Cl2
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DOI：
10.1007/s00214-012-1194-y
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发表时间：
2012-03
影响因子：
1.7
通讯作者：
Qingyong Meng;Hua Dong;Ming-Bao Huang
中科院分区：
文献类型：
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作者：
Qingyong Meng;Hua Dong;Ming-Bao Huang
为了研究ClO（X2 <$）+ ClO（X2 <$）→ ClOOCl → 2Cl（2 Pu）+ O2（X3 <$g−）反应（1）和ClO（X2 <$）+ ClO（X2 <$）→ ClOOCl → Cl 2（X1 <$g+）+ O2（X3 <$g−）反应（2）的绝热和非绝热机理，我们在C2约束下通过部分几何优化方法计算了ClO（X2 <$）+ ClO（X2 <$）→ ClOOCl → Cl 2（X1 <$g+）+ O2（X3 <$g −）反应（2），在CASPT ~ 2水平上计算了ClOOCl分子的五个低激发态的O-O和O-Cl离解势能曲线。还确定了11 A基态[与反应（1）的产物相关]和13 B态[与反应（2）的产物相关]的势能面之间的CASSCF最小能量交叉点（MECP）。根据CAS计算结果（佩奇、能量和MECP处的自旋轨道耦合），我们预测反应（1）沿沿着途径1发生：ClO（X2 Pu）+ ClO（X2 Pu）→ ClOOCl（11 A）→ 2Cl（2 Pu）+ O2（X3 Pu g−），反应（2）沿沿着途径2发生：ClO（X2）+ ClO（X2）→ ClOOCl（11 A）→ 11 A/13 B MECP（142.4 cm−1）→ ClOOCl（13 B）→ Cl2（X1 g+）+ O2（X3 g−）。反应途径1和2所需能量（相对于反应物）分别为5.3和11.1 kcal/mol，表明反应（1）比反应（2）更有利。本工作支持传统的臭氧光化学降解模型：ClOOCl（11 A），由两个ClO（X2）形成，可以直接产生O2+两个Cl原子。
For studying the adiabatic and nonadiabatic mechanisms of the ClO (X2Π) + ClO (X2Π) → ClOOCl → 2Cl (2Pu) + O2(X3Σg−) reaction (1) and the ClO (X2Π) + ClO (X2Π) → ClOOCl → Cl2(X1Σg+) + O2(X3Σg−) reaction (2), we calculated, by partial geometry optimizations under the C2constraint, the O–O and O–Cl dissociation potential energy curves (PECs) from the five low-lying states of ClOOCl at the CASPT2 level. The CASSCF minimum-energy crossing point (MECP) between the potential energy surfaces of the 11A ground state [correlating with the product of reaction (1)] and the 13B state [correlating with the product of reaction (2)] states was also determined. Based on the CAS calculation results (PECs, energies, and spin–orbit coupling at the MECP), we predict that reaction (1) occurs along pathway 1: ClO (X2Π) + ClO (X2Π) → ClOOCl (11A) → 2Cl (2Pu) + O2(X3Σg−) and that reaction (2) occurs along pathway 2: ClO (X2Π) + ClO (X2Π) → ClOOCl (11A) → 11A/13B MECP (142.4 cm−1) → ClOOCl (13B) → Cl2(X1Σg+) + O2(X3Σg−). The needed energies (relative to the reactant) for pathways 1 and 2 are predicted to be 5.3 and 11.1 kcal/mol, respectively, which indicates that reaction (1) is more favorable than reaction (2). The present work supports the traditional photochemical model for ozone degradation: ClOOCl (11A), formed by two ClO (X2Π), can directly produce O2plus two Cl atoms.