La_(2)与La_(n)F(n＝1,2)分子的结构与势能函数

Structures and potential energy functions of La_(2) and La_(n)F(n=1,2) molecules

采用密度泛函理论确定La2与LanF（n=1，2）分子的电子与结构特性．应用最小二乘法拟合出La2和LaF分子的Murrell—Sorbie势能函数，在此基础上推导出光谱数据和力常数．基态LazF分子具有C2，对称性的弯曲结构，电子态4A2，结合能为7．89eV．用多体项展式理论得出LazF的解析势能函数，其等值势能图准确再现了LazF分子的平衡结构．

Density functional method has been used to determine the electrical and structural properties of La2and LanF（n= 1, 2）. The Murrell-Sorbie potential energy functions of La2 and LaF molecules have been derived to be fitted to ab initio data through the least square fitting. The ground state of La2 F mol- ecule has C2 symmetry and is in the 4A2state,the binding energy B~ equals 7.89 eV. The analytical po- tential energy function of La2 F is driven by many-body expansion theory. The contour lines constructed describe correctly the balance structure of La2 F molecule.