B_2分子X^3Σ_g^-和A^3Σ_u^-态的势能函数

Potential Energies of Electronic States X^3Σ_g^- and A^3Σ_u^- of a B_2 Molecule

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.

The energies, equilibrium geometries and harmonic frequencies of the ground state X^3∑g^- and the first excited state A^3∑u^- of a B2 molecule are calculated using the GSUM （Group Sum of Operators） method of SAC/ SAC-CI with the basic sets D95（d）, 6- 311g^＊＊ and cc- PVTZ. It is found that the basis set D95（d） is suitable for the energy calculation of a B2 molecule. The potential curves are scanned using the SAC/D95（d） method for the ground state and the SAC-CI/ D95（d） methods for the excited states. A least square is fitted to a Mttrrell-Sorbie function. The spectroscopy constants （Be, ae, ωe, and ωe χe ） are calculated which are in good agreement with experiment. It is believed that the Murrell-Sorbie function and the SAC/ SAC-CI method are suitable not only for the ground state, but also for low-lying excited states.