基态SiH^+分子离子光谱常数与振动能级研究

Study on the Spectroscopic Data and Vibrational Levels of the Ground SiH^+ Molecular Ion

首先根据群论及原子分子反应静力学的相关知识,推导了SiH+分子离子基态X1Σ+的电子态和合理的离解极限。然后采用Gaussian 09程序包中优选出的QCISD(T)方法结合cc-pVQZ基组,对SiH+分子离子基态结构进行了优化计算。运用相同方法对SiH+分子离子基态进行了单点势能扫描,分别采用9参数Murrell-Sorbie函数及Murrell-Sorbie+c6函数进行了非线性最小二乘拟合,首次得到了SiH+分子离子基态的势能函数和相应的光谱常数ωe,ωexe,Be,αe。计算结果表明,利用9参数Murrell-Sorbie函数计算所得的光谱常数与实验光谱数据吻合得更好,相对误差分别为0.13%,3.07%,0.38%,5.25%以及0.52%,这些数据均说明9参数Murrell-Sorbie势能函数能更好地描述SiH+分子离子基态的性质,拟合所得势能曲线准确地再现了其离解能和平衡结构特征。通过求解双原子分子核运动的径向薛定谔方程,首次报道了SiH+分子离子基态在J=0时的振动能级、转动惯量和六个离心畸变常数。为实验上找到对应的跃迁提供了理论依据。

The ground electronic state and the reasonable dissociation limit of SiH^＋molecular ion 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 SiH^＋molecular ion have been calculated using the method QCISD（T）/cc-pVQZ.The whole potential curves for the ground electronic state is further scanned using the above method,the potential energy functions and relevant spectroscopic constants of this state are then first obtained by least square fitting to the Murrell-Sorbie function（n=9）and the modified Murrell-Sorbie＋c6function,respectively.The present results showed that the calculated results based on the MurrellSorbie function（n=9）are in better agreement with the experimental values,with the relative errors between spectroscopic constants and the experimental values being 0.13%,3.07%,0.38%,5.25% and 0.52%respectively.With the potential obtained at the QCISD（T）/cc-pVQZ level of theory,the total of 27 vibrational states are predicted when J=0by numerically solving the radial Schrodinger equation of nuclear motion.The complete vibrational levels,inertial rotation and six centrifugal distortion constants are obtained for the ground electronic state of SiH^＋molecular ion for the first time.Calculation results in the present work may provide theoretical supports for the further study of SiH^＋molecular ion.