BF分子X1Σ＋, A1P和B1Σ＋态的势能函数

使用SAC/SAC-CI和D95＋＋, 6-311＋＋g, 6-311＋＋g**及D95(d)基组, 分别对BF分子的基态X¹Σ^＋、第一简并激发态A¹Π和第二激发态B¹Σ^＋的平衡结构和谐振频率进行优化计算. 对所有计算结果进行比较, 得出6-311＋＋g**基组为最优基组. 运用6-311＋＋g**基组和SAC方法对基态X¹Σ^＋, SAC-CI方法对激发态A¹Π和B¹Σ^＋进行单点能扫描计算, 并用正规方程组拟合Murrell-Sorbie函数, 得到相应电子态的势能函数解析式, 由得到的势能函数计算了与X¹Σ^＋, A¹Π和B¹Σ^＋态相对应的光谱常数, 结果与实验数据较为一致.

Potential Energy Functions for the Electronic States X1Σ＋, A1P and B1Σ＋ of Molecule BF

The energies, equilibrium geometries and harmonic frequencies of the ground state X¹Σ^＋, the first degenerate state A¹P and the second state B¹Σ^＋of molecule BF have been calculated using the method Group Sum of Operators of SAC/SAC-CI with the basis sets D95＋＋, 6-311＋＋g, 6-311＋＋g** and D95(d). Comparing the four basis sets abovementioned, the conclusion was gained that the basis set 6-311＋＋g** was the most suitable for the energy calculation of molecule BF. The whole potential curves for these three electronic states were further scanned adopting SAC/6-311＋＋g** method for the ground state and SAC-CI/6-311＋＋g** method for the excited states, then a least square was fitted to Murrell-Sorbie function, and last the spectroscopy constants were calculated, which are in better agreement with the experimental data. It was believed that Murrell-Sorbie function form and SAC/SAC-CI method were suitable for not only the ground state, but also the low-lying excited states.