密度泛函理论研究大气中Br与HCNO的反应机理

DFT investigation on the reaction mechanism for the reaction of atomic radical Br with HCNO in the atmosphere

采用密度泛函理论(DFT)研究了大气中Br与雷酸(HCNO)分子反应的机理.在B3LYP/6-311++G**水平上,优化得到了反应物、过渡态、中间体和产物的几何构型;利用CCSD(T)/6-311++G**方法对各驻点的单点能量进行校正;通过振动分析对过渡态和中间体构型进行了确认.计算结果表明:Br与HCNO分子的反应有两种不同的反应机制.其中,Br加成到HCNO分子中O原子上消去OBr基团的反应是主反应通道,且P1(HCN+OBr)为主产物.

The reaction mechanisms of atomic radical Br with HCNO in the atmosphere were investigated with the DFT. The geometrical parameters of the reactants, transition states, intermediates and the products were optimized at B3LYP/6-311＋＋G＊ ＊. The single point energies of the species were cor- rected at the CCSD（T）/6-311＋ ＋G ＊＊ level, and the intermediates and transition states were detected by the frequency analysis. The calculation results show that the Br＋ HCNO reaction has two different mechanisms. The dominant reaction channel is atomic radical Br added to the terminal O-atom of HC- NO, followed by the elimination of OBr. And consequently the major product is PI（HCN＋OBr）.