KH(KD)分子基态(X^1Σ^+)的结构与势能函数研究

Structure and Potential Energy Function of the Ground State of KH (KD) Molecule

利用群论及原子分子反应静力学的有关原理,推导了KH(KD)分子基态X1Σ+的电子态和合理的离解极限.采用Gaussian03程序包中的多种方法和基组,对KH(KD)分子基态X1Σ+的平衡结构和谐振频率进行了优化计算.通过比较计算结果,发现B3LYP为最优方法,6-311g(3df,3pd)为最佳基组.运用优选出的方法和基组对KH(KD)分子基态进行了单点势能扫描,然后分别采用Murrell-Sorbie函数及修正的Murrell-Sorbie+c6函数进行了非线性最小二乘拟合,得到了KH(KD)分子基态的势能函数和相应的光谱常数.计算结果表明,利用修正的Murrell-Sorbie+c6函数计算所得的光谱常数与实验数据吻合得更好.

The equilibrium geometries of the ground electronic states X^1Σ^＋ and the dissociation limit of KH （KD） molecule have been correctly determined based on group theory and atomic and molecular reaction statics. The energy, equilibrium geometry and harmonic frequency of the ground electronic state of KH （KD） have been calculated using several methods in conjunction with different basis sets. Comparing the computational results, the conclusion was obtained that B3LYP/6-311g （3df, 3pd） is the most suitable for the energy calculation of KH （KD） molecule. The whole potential curves for the ground electronic state were further scanned using the above method, the potential energy functions and relevant spectroscopic constants of this state were then obtained by least square fitting to the Murrell-Sorbie function and the modified Murrell-Sorbie＋c6 function, respectively. The present results showed that the calculated results based on the modified Murrell-Sorbie＋c6 function were in good agreement with the experimental values.