LaO分子基态X^2Σ^+势能和平衡几何构型的比较研究

Comparative investigation to potential energy and geometrical structure of ground state X^2Σ^+ of molecule LaO

采用三种相对论有效核芯势 (LanL2DZ ,AREP ,RCEP)和价电子基组在MP2、B3LYP、CCSD(T)和QCISD(T)水平上计算了LaO分子基态平衡几何构型和能量 ,并对各种计算方法在不同基组下的计算效率和精度等进行了综合比较。在此基础上 ,选用B3LYP方法进行能量扫描得到了LaO分子势能曲线。计算得到的LaO分子基态平衡几何 ,振动频率、解离能和力常数等均与实验结果吻合。最后对赝势方法计算的误差原因进行了分析。

The potential energy and geometrical structure of ground state X^2Σ^+ of molecule LaO are calculated at the level of MP2, B3LYP,CCSD(T) and QCIST(T) using three kinds of relativistic effective core potentials (LanL2DZ, AREP, RCEP) and valence electrons basis sets. The efficiencies and precisions of calculation methods under different basis sets are compared comprehensively. Then the potential curve of LaO molecule is gotten by potential scan with B3LYP. The calculated ground state equilibrium geometry, viberational frequency, dissociation energy and force constants are in good greement with experimental valves. Finally the reason of calculation errors with pseudopotential is studied.