自由基OH(X^2 Π,A^2 Σ^+)的从头算研究

An ab initio study of the radical OH(X^2Π,A^2Σ^+)

用分子轨道从头算方法 ,研究了OH分子的基态 (X2 Π)和激发态 (A2 Σ+ )。结果表明 ,对于基态 ,在QCISD(T) / 6 - 311++G(3df ,3pd)理论水平上 ,键距是 0 .0 970 4nm ,与实验值 0 .0 970 6nm完全吻合。对于激发态 ,使用完全活性空间方法 (CASSCF)和大基组 6 - 311++G(3df ,3pd) ,键距是 0 .10 0 98nm ,与实验值 0 .10 12 1nm基本吻合。从激发态A2 Σ+ (ν =0 )到基态X2 Π(ν=0 )的垂直跃迁能量是 4 .4 6 92eV ,与实验值 4 .3980eV也吻合较好。

The ground state X 2Π and excited state A 2Σ + of OH molecule have been studied using ab initio method. At the theoretical level QCISD( T )/6-311++G( 3df,3pd) , the calculated bond length of the ground state is 0.097 04 nm. For the excited state, the calculated bond legnth obtained by CASSCF at the large radical basis set is 0.100 98 nm. The calculated vertically excited energy from excited state A 2Σ +(ν=0) to ground state X 2Π(ν=0) is 4.469 2 eV. All our calculated theoretical results are in good agreement with the experimental values 0.09 706 nm, 0.101 21 nm and 4.398 0 eV respectively.