Na_2H的基态结构与势能函数

Ground equilibrium structure and analytical potential energy function for Na_2H

采用二次组态相关(QCISD)方法对NaH分子进行理论计算,得到它的几何结构、光谱性质,并拟合出它的Murrell-Sorbie势能函数.应用密度泛函(B3LYP)方法,在6-311G(3df,3pd)基组水平上对Na2H分子的基态结构进行优化,并用同样的基组对该分子进行了进一步的频率计算.结果发现Na2H分子的基态稳态结构为C2v构型,采用多体项展式理论导出了它的解析势能函数,其等值势能图准确再现了Na2H分子的结构特征和离解能.并报导了该分子对称伸缩振动等值势能图中存在的两个对称鞍点,对应于反应NaH+Na→Na2H,活化能大约为14.56 kJ/mol.

The energy, equilibrium geometry and harmonic frequency of the ground state of Nail molecule have been calculated using the quadratic configuration interaction （QCISD） method with the basis set 6-311G （3df,3pd）. The potential curve for this molecule have a least square fitted to Murrell-Sorbie function. The spectroscopy constants （Be, αe,ωe and ωeχe） are calculated, which are in good agreement with the experimental data. B3LYP method are used to optimized the ground-state structure of Na2H. The results show that the ground state of Na2H is of C2v symmetry and of X^2A1 state, the equilibrium bond length RNa-H equals 0. 20635 nm, the bond angle ∠NaHNa equals 95. 1028°, the dissociation energy De equals 0. 650969 eV and the harmonic frequencies are v1 （ α2 ） = 149. 7684 cm^-1, v2 （b2） = 7224602 cm^-1, v3 （ α2 ） = 7887. 3346 cm^-1. The potential energy function of Na2H （C2v, X^2A1 ） is derived from the many-body expansion theory. The potential energy function describes correctly the configuration and the dissociation energy.