CO与HO2或NO2反应机理的计算研究

用密度泛函DFT（B3LYP）方法和MP2从头算方法，在6-311G（d，p），6-311＋＋G（d，p）基组水平上研究了CO＋HO2-C02＋OH，CO＋NO2-CO2＋NO2个反应的过渡态结构和反应机理，沿IRC分析指出反应均为协同完成的一步反应．同时计算了2个反应的活化位垒和反应焓变，并与实验估计值进行了比较．对CO与H02的反应采用MP2／6—311＋＋G（d，p）方法，计算所得反应位垒为100．98kJ／mol，与实验估计值93．60kJ／mol基本接近，对CO与N02的反应采用B3LYP／6—311＋＋G（d，p）方法，计算所得反应位垒为115．99kJ／mol，比实验估计值141．51kJ／mol低25．52kJ／mol．计算同时表明2个反应均为放热反应．

Theoretical Studies on the Reaction of CO with HO2 or NO2

The reaction mechanism of reactions CO+HO2=CO2+OH(1) and CO+NO2=CO2+NO(2) was theoretically studied with DFT(B3LYP) and MP2.The geometry and energy of reactants,transitional states and products were optimized at the 6-311G(d,p) and 6-311++G(d,p) levels.Based on IRC,the calculated results indicated that reaction(1) and(2) are all the concerted one-step processes.The energy barrier and enthalpy for the reactions were also calculated and compared with experimental findings.The energy barrier of the reaction(1) was 100.98 kJ/mol by using MP2/6-311++G(d,p).The difference is less between the value and the experimental value 96.30 kJ/mol.And the reaction(2) was 115.99 kJ/mol by using B3LYP/6-311++G(d,p),with the experimental value 141.51 kJ/mol only differs 25.52 kJ/mol.The results showed that both the reactions were the exothermal.