The splitting of potential energy curves for the states X^2Ⅱ3/2, ^2Ⅱ1/2 and A^2∑＋ of hydroxyl OH under spin-orbit coupling （SOC） has been calculated by using the SO multi-configuration quasi-degenerate perturbation theory （SO- MCQDPT）. Their Murrell Sorbic （M-S） potential functions have been derived, then, the spectroscopic constants for X^2Ⅱ3/2, ^2Ⅱ1/2 and A^2∑＋ have been derived from the M-S function. The calculated dissociation energies for the three states are Do[OH（X^2Ⅱ3/2）]=34966,632cm^-1, Do[OH（^2Ⅱ1/2）]=34922.802cm^-1, and Do[OH（A^2∑ ）]=17469.794cm^-1, respectively. The vertical excitation energy u[^2Ⅱ1/2（v = 0） → X^2Ⅱ3/2（v = 0）] = 139.6cm^-1. All the spectroscopic data for the X^2Ⅱ3/2 and ^2Ⅱ1/2 are given for the first time except the dissociation energy of X^2Ⅱ3/2.
使用SAC/SAC-CI方法,利用D95(d),6-311g**以及cc-PVTZ等基组,对B2分子的基态(X3Σg-)和第一激发态(A3Σu-)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了D95(d)基组为3个基组中的最优基组的结论;使用D95(d)基组,利用SAC的GSUM(Group Sum of Operators)方法对基态(X3Σg-),SAC-CI的GSUM方法对激发态(A3Σu-)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X3Σg-)和第一激发态(A3Σu-)相对应的光谱常数(Be,αe,ωe和ωeχe),结果与实验数据吻合.
