双自由基CH燃烧反应机理的研究

A theoretical study of the reaction mechanism of combustion of the bi-radical CH

应用量子理论从头算和密度泛函理论(DFT)对双自由基CH(X2Π)与O2(X3∑g-)的反应机理进行了研究.在B3PW91/6-311G**水平上优化了反应通道上各驻点(反应物、中间体、过渡态和产物)的几何构型,并计算了零点能和过渡态的虚频率.并由B3PW91/6-311G**给出了各物种的总能量.计算表明,反应物中自由基CH与O2反应主要在二重态势能面上进行,CH中的C原子可以插在O2分子中两个氧原子中间形成中间体1(2HCO2),中间体1(2HCO2)可以经过不同的反应通道形成不同的产物P1(1CO2+2H)和P2(1CO+2OH),各反应通道的反应热的计算与实验值吻合较好.

Using the density function theory （DFT） and ab initio calculation, the reaction of CH radical with O2 was studied. At 6-311G^＊＊ level with DFT method, the geometries of all species （reactant, transition states, intermediate ana products） were optimized and zero point energy （ZPE） and the transition states＇ imaginary frequencies were also calculated. The calculation results suggest that C atom of the CH radical insert into the O2 bond leading to IM1 （2^HCO2）. The IM1 （2^HCO2） undergoes different channels and can form different products, i.e. P1 （1^CO2 ＋ 2^H） and P2 （1^CO ＋ 2^OH）- This investigation could excellently explain the experiment of the title reaction.