【摘要】 使用SAC/SAC-CI方法,利用6-311++g,6-311g**及cc-PVTZ等基组,对Na2分子的基态(X1Σg+)、第一激发态(A1Σu+)和第二激发态(B1Πu)的平衡结构和谐振频率进行计算.通过对3个基组的计算结果的比较,得出6-311g**基组为3个基组中最优基组的结论;使用6-311g**基组,分别利用SAC的GSUM(Group Sum of Operators)方法对基态(X1Σg+),SAC-CI的GSUM方法对激发态(A1Σu+)和(B1Πu)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的完整势能函数.用得到的势能函数计算与基态(X1Σg+),第一激发态(A1Σu+)和第二激发态(B1Πu)相对应的光谱常数(Be,αe,ωe和ωeχe),结果与实验数据基本吻合.更多还原

【Abstract】 The energies,equilibrium geometries and harmonic frequencies of X¹Σ⁺_g,A¹Σ⁺_u and B¹Π_u of molecule Na₂ are calculated by the GSUM（Group Sum of Operators） method of SAC/SAC-CI using basis sets 6-311++g,(6-311g^**) and cc-PVTZ.It is found that(6-311g^**) is suitable for energy calculation of molecule Na₂.The potential curves of ground states and excited states are scanned by the SAC/6-311g^** and SAC-CI/6-311g^** methods,respectively.A least square is fitted to a Murrell-Sorbie function.The spectroscopy constants （B_e,α_e,ω_e,and ω_eχ_e） are calculated and show good agreement with experiment.It is believed that Murrell-Sorbie function and the SAC/SAC-CI method are suitable for ground states and for low-lying excited states as well.更多还原