PuC_2基态分子的结构与多体展式势能函数

Structure and Analytic Potential Energy Function for Ground State of PuC_2 Molecule

用相对论有效原子实势和密度泛函理论方法对PuC和PuC2 分子的结构进行优化 ,得到了其平衡几何构型和谐振频率 .采用最小二乘法拟合出PuC基态分子的Murrell Sorbie解析势能函数 ,在此基础上推导出光谱数据和力常数 ,并用多体展式理论导出PuC2 基态分子的解析势能函数 ,正确地反映其平衡构型特征 .

The equilibrium geometry of PuC and PuC_ 2 molecule have been firstly calculated on the computational levels of density functional theory (DFT) with the relativistic effective core potential and the valence basis sets. The possible electronic state and its reasonable dissociation limit for the ground state of PuC and PuC_ 2molecule are determined based on atomic and molecular reaction statics. Theequilibrium structure of ground state for PuC and PuC_ 2molecule havebeen optimized to be X 5Σ -,R_ C-Pu =0.224 nm,dissociation energy D_ e=3.0705 eV for PuC moleculeand 3 A_ 2,R_ C-Pu = 0.23116 nm,R_ Pu-C = 0.23116 nm,∠CPuC=140.29°,dissociation energy D_ e=3.794 eV,harmonic frequencies ν_ 1(A_ 1) =137.2898 cm -1,ν_ 2(A_ 1)=335.6757 cm -1,ν_ 3(B_ 2)=418.0143 cm -1for PuC_ 2molecule,respectively. Murrell-Sorbie analytic potential energy function of PuC molecule has been derived to be fitted to ab initio data through the least-square fitting,and harmonic frequency,force constant and spectroscopic data have been derived for the first time. The analytic potential energy function of PuC_ 2molecule is derived by many-body expansion theory. The stretch potential surface and the rotational potential surface of PuC_ 2show that it is easily to form PuC_ 2 molecules from Cand PuCmolecules with no threshold.