多组态二级微扰理论计算CH_3O_2激发光谱以及CH_3O_2→CH_3+O_2解离反应  

Excited Spectroscopy and O_2-loss Dissociations in Low-lying Electronic States of CH_3O_2 Studied Using Multiconfiguration Second-Order Perturbation Theory

作　　者：侯春园[1] 郑清川[1] 舒鑫[1] 张红星[1] 

机构地区：[1]吉林大学理论化学研究所理论化学计算国家重点实验室,长春130061

出　　处：《化学学报》2007年第18期1947-1950,共4页Acta Chimica Sinica

基　　金：国家自然科学基金(Nos.20573042;20333050;20173021)资助项目.

摘　　要：在Cs对称性和aug-cc-pVTZ基组水平下,采用全活化空间自洽场方法(CASSCF)研究了CH3O2自由基基态及其阴阳离子的12个低激发态.为了进一步考虑动态电子相关效应,采用二级多组态微扰理论(CASPT2)获得更加精确的能量值.所有计算得到的电子态都是价电子态,而且所得绝热激发能和电子亲和势与实验值非常接近.在CASPT2//CASSCF理论水平下计算了CH3O2从2A"和2A'电子态的CH3O2→CH3+O2的解离反应的势能曲线(PECs).优化得到的裂解产物的几何结构和能量与分别优化CH3和O2得到的结果进行比较,从而确定裂解产物的电子态.结果表明,从2A"和2A'电子态的解离反应分别对应产物CH3(2A")+O2(3A")和CH3(2A")+O2(1A").Complete active space self-consistent field （CASSCF） calculations with aug-cc-pVTZ basis sets were performed for twelve low-lying electronic states of the methyl peroxy radical CH3O2 and its positive and negative ions in Cs symmetry. The accuracy of the energies were improved by including dynamic electron correlation by the multiconfiguration second-order perturbation theory （CASPT2） method. All calculated states are valence states. The calculated adiabatic excitation and affinity energies are in reasonable agreement with the experimental data. Potential energy curves （PECs） for O2-loss dissociation from the ^2A″ and ^2A＇ states were calculated at the CASPT2//CASSCF level and the electronic states of the O2 and CH3 as the dissociation products were carefully determined by checking the relative energies and geometries of the asymptote products along the PECs. The O2-loss PEC calculations for CH3O2 indicate that O2-loss dissociation occurs from the 2A″ and 2A＇ states leading to CH3（^2A″）＋O2（^3A″） and CH3（^2A″）＋O2（^1A″）, respectively.

关 键 词：甲基双氧 多组态自洽场理论 多组态二级微扰理论 势能曲线 

分 类 号：O643.12[理学—物理化学]