利用分子反应静力学的原理.确定了^7LiH分子X^1∑^+态的合理离解极限;使用HF、QCISD、QCISD(T)、B3LYP和B3P86等方法。6-311G、6-311G(d,p)、6-311G(3df, 3pd)、D95V(d,P)和D95V(3df, 3dp)等基组.对^7LiH分子X^1∑^+态的平衡核间距、谐振频率和离解能进行了优化计算,且将计算结果(平衡挂间距0.1609nm、谐振频率1390.51cm^-1、离解能2.474eV)与实验结果(平衡核间距0.1596nm、谐振频率1405.7cm^-1、离解能2.515eV)进行了比较,得出了包含单、双取代并加入三重激发贡献的QCISD(T)方法为最优方法、基组6-311G(3df,3pd)为最优基组的结论,在QCISD(T)/6-311G(3df,3pd)理论水平。对^7LiH分子的X^1∑^+态进行了单点能扫描。并用最小二乘法拟合出了其解析势能函数;从拟合出的解析势能函数出发,计算出了X^1∑^+态的光谱常数Be, αe和ωeXe(其值分别为7.379cm^-1、0.1976cm^-1和21.697cm^-1),以及二阶、三阶和四阶力常数f2、f3和f4(其值分别为106.378J·nm^-2、-3650.4aJ·nm^-3和112176.2aJ·nm^-4).
The reasonable dissociation limit of the X^1∑^+ state 7 LiH molecule is attained by using the molecular reaction static theory. The equilibrium separation of 0. 160 9 nm, the harmonic vibrational frequency of 1 390.51 cm^-1 and the dissociation energy of 2.474 eV about this state are accurately calculated by using such methods as HF,QCISD,QCISD(T) ,B3LYP and B3P86 with the basis sets 6-311G,6-311G(d,p) ,6-311G(3df, 3 pd), D95 V ( d, p) and D95 V (3 dr,3 pd). Comparing the attained results with the experiments, the conclusion is gained that the QCISD(T)/6-311G(3df,3pd) is the most suitable for the ground-state energy calculation of ^7LiH molecule. The whole potential energy curve for this state is further scanned at the QCISD(T)/6-311G (3dr, 3pd) theory level,then has a least squares fitted to the analytic Murrell-Sorbie function form,and last the spectroscopy data (Be = 7. 379 cm^-1, αe = 0. 197 6 cm^-1 and ωeXe = 21. 697 cm^-1 ) and force constants (f2 = 106.37 aJ · nm^-2, f3 =-3 650.4 aJ · nm^-3 and f4 =112 176.2 aJ · nm^-4) are calculated.