LaF分子基态X^1Σ^+分析势能函数计算

Calculation on analytic potential energy function for ground state X^1Σ^+ of LaF

用原子分子反应静力学原理导出LaF分子可能的电子状态和离解极限。在相对论有效核芯势RECP(RelativisticEffectiveCorePotential)近似下 ,用密度泛函理论中的B3LYP方法优化了LaF分子单、三重态平衡几何结构 ,计算了基态X1Σ+ 的振动基频和离解能。在计算出来的一系列单点势能基础上 ,用非线性最小二乘方法拟合出基态Murrell Sorbie势能曲线 ,得到分析势能函数 ,由此计算出相应光谱常数ωe、Be、αe、ωeχe的理论值并和实验测量的振转光谱比较 ,结果非常吻合。另外还比较了用两种不同有效势得到的分析势能函数和光谱参数 ,以能量一致相对论有效势ECEP(EnergyCosistentRelativisticEffectivePotential)得到的结果最好。

The possible electronic states and their reasonable dissociation limits for LaF are determined based on Atomic and Molecular Reaction Statics(AMRS). The equilibrium geometries of singlet and triplet states have been optimized with B3LYP method of Density Function Theory(DFT) using three types of Relativistic Effective Core Potentials(RECPs). The harmonic frequency and dissociation energy of the ground state have also been calculated. After potential energy curve scan, Murrell Sorbie potential energy function of the ground state X 1Σ + has been derived with a nonlinear least square fit. The calculated spectroscopic constants such as ω e?B e?α e?ω eχ e are in good agreement with the experimental results of vibration rotational spectra. In addition the potential energy functions and corresponding spectroscopic constants derived by two different RECPs are also compared and discussed. The results obtained from ECEPs(Energy Consistent Relativistic Effective Potentials) are better.