基态~7Li_2(X^1Σ_g^+)分子的解析势能函数

Analytical Potential Energy Function of the Ground State X^1Σ_g^+~7Li_2 Molecule

利用分子反应静力学的原理,导出了7L i2分子X1Σg+态的合理离解极限;使用HF、B3LYP、B3P86、QC ISD和QC ISD(T)方法和D95、D95V、D95V(d,p)、D95V(3df,3pd)、6-311G、6-311G(d)、6-311G(d,p)、6-311G(3df,3pd)基组,对7L i2分子X1Σg+态的平衡几何、谐振频率和离解能进行了优化计算,比较得出QC ISD(T)/6-311G(3df,3pd)为最优方法/基组.在QC ISD(T)/6-311G(3df,3pd)水平下,对7L i2分子X1Σg+态进行了单点能扫描,并用正规方程组拟合出了其解析势能函数.根据拟合出的解析势能函数计算出了X1Σg+态的光谱常数Be=0.656 cm-1,αe=0.006 cm-1和ωeeχ=2.85 cm-1及二阶、三阶和四阶力常数f2=26.159 aJ.nm-2,f3=-533.479 aJ.nm-3和f4=5 688.5 aJ.nm-4.

The reasonable reaction dynamics theory dissociation limit of the X^1∑g^＋ state of ^7Li2 molecule is attained by using the molecular The equilibrium geometry, harmonic frequency and dissociation energy about this state are accurately calculated by using such methods as HF,B3LYP, B3P86,QCISD,QCISD（T） and B3P86 with the basis sets D95, D95V, D95V（ d ,p）, D95V（3df,3pd） ,6-311 G,6-311 G（d） ,6-311 G（d,p） ,6-311G（3df,3pd）. 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 ^7Li2 molecule. The whole potential energy curve for this state is further scanned at the QCISD （T）/6-311G （3df, 3pd） theory level, and then has a least squares fitted to the analytic Murrell-Sorbie function form. The spectroscopy data （ Be = 0. 656 cm^-1 , αe = 0. 006 cm^-1 and ωeχe=2.85cm^-1） and force constants （f2 =26. 159 aJ·nm^-2,f3 =-533.479 aJ·nm^-3 andf4 = 5 688.5 aJ ·nm^-4） are calculated.