氧气和CS自由基反应势能面的密度泛函理论研究

应用量子化学从头计算和密度泛函理论(DFT)对O_2和CS自由基的反应进行了研 究。在B3LYP/6-311G~(**)水平上计算出了各物种的优化构型、振动频率和零点振 动能(ZPVE)。各物种的总能量由CCSD（T）/6-311G~(**)//B3LYP/6-311G~(**)给出 ，并对总能量进行了零点能校正。计算结果表明：CS自由基中的C端沿着O_2的双键 中线方向进攻，进行加成反应，反应的第一步放出大量的热量(450 kJ/mol)，推动 反应继续进行，从稳定的中间体4(Cs)出发，反应主要通过O的相邻位置的迁移生成 P_1(CO+SO)和P_3(COS+O)；通过S的相邻位置的迁移生成了重要的反应复合物 (complex 1)，进一步离解为产物P_2(CO_2+S)。计算结果可以很好地解释反应机理 。

Theoretical Study on Reaction Mechanism of the CS Radical with Oxygen

The singlet potential energy surface for the CSO 2 system was investigated at the hybrid density functional B3LYP and CCSD(T) (single point) levels with 6 311G ** basis set in order to clarify the reaction mechanism of the radical CS with oxygen. It is shown that the C site of the CS radical attacks the O 2 bond and forms the isomer 4. The entrance step gives out a lot of energy. The isomer 4 undergoes the 1,2 O atom shift or the 1,2 S atom shift and ultimately forms the products. This mechanism can excellently express the formation of the P 1 (CO+SO), P 2 (CO 2+S) and P 3 (COS+O).