H_2分子X1Σ_g^+,B^1Σ_u^+和C^1Π_u态的势能函数

Analytical potential energy functions for the electronic states X^1Σ_g^+,B^1Σ_u^+ and C^1Π_u of molecule H_2

使用SAC/SAC-CI方法,利用D95++LL、6-311++gLL以及cc-PVTZ等基组,对H2分子的基态X1Σ+g、第二激发态B1Σ+u及第三简并激发态C1Πu的平衡结构和谐振频率进行了优化计算。通过对三个基组的计算结果的比较,得出了cc-PVTZ基组为三个基组中的最优基组的结论;使用cc-PVTZ基组,利用SAC的GSUM(Group Sumof Operators)方法对基态X1Σ+g、SAC-CI的GSUM方法对激发态B1Σu+和C1Πu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X1Σg+、第二激发态B1Σ+u和第三简并激发态C1Πu相对应的光谱常数(Be,αe,ωe和ωeχe),结果与实验数据基本一致。

The energies,equilibrium geometries and harmonic frequencies of the three electronic states(the ground state X1Σ+g,the second excited state B1Σ+u and the third excited state C1Πu) of H2 molecule have been calculated using the GSUM(Group Sum of Operators) method of SAC/ SAC-CI with the basis sets D95++**,6-311++g** and cc-PVTZ.Comparing among the above-mentioned three basis sets,the conclusion is gained that the basis set cc-PVTZ is the most suitable for the energy calculation of H2 molecule.The whole potential curves for these three electronic states are further scanned using SAC/cc-PVTZ method for the ground state and SAC-CI/cc-PVTZ methods for the excited states,then have a least square fitted to Murrell-Sorbie function,and last the spectroscopy constants(Be,αe,ωe,and ωeχe) are calculated,which are in good agreement with the experimental data.It is believed that Murrell-Sorbie function form and SAC/ SAC-CI method are suitable not only for the ground state,but the low-lying excited states as well.