SeOx(x=1,2)的从头算势能曲线和光谱常数

采用从头算的多种方法和基组优化计算SeO_x(x=1,2)自由基的基态结构、谐振频率及离解能,优选出QCISD(T)/6-311+G(2df)、B3LYP/6-311G(3d2f)方法分别对SeO、SeO₂自由基进行计算,计算结果与实验结果吻合很好.对SeO自由基拟合出Murrell-Sorbie势能函数参数,计算出SeO自由基的光谱常数和力常数.计算出SeO₂自由基力常数,导出SeO₂自由基的多体展式势能函数,发现SeO₂自由基对称伸缩振动势能图中在对称的O+SeO→SeO₂反应通道上有一鞍点,其活化能约为48.24 kJ·mol^-1,O原子需要越过0.5 eV的能垒才能生成SeO₂的稳定结构.

ab Initio Potential Energy Curves and Spectral Constants of SeOx(x=1,2)

Possible ground state structures, harmonic frequency and dissociation energy of SeO_x(x=1,2) free radical are optimized by different methods and base sets included in Gaussian 09. Among them, QCISD(T)/6-311+G(2df) and B3LYP/6-311G(3d2f) are the most suitable for SeO, SeO₂. Calculation results are in good agreement with experiment. For SeO free radical, Murrell-Sorbie potential energy functional constant are calculated, according to which spectral parameters and force constants are shown. It provides basis for further investigation on SeO_x(x=1,2). For SeO₂ free radical, force constants are calculated at the same time. And potential energy functions of SeO₂ are derived with many-body expansion theory. In a symmetric stretching vibration potential energy diagram of SeO₂, saddle points in reaction kinetics O+SeO→SeO₂ in the symmetry dilation potential energy are found. Activation energy is 48.24 kJ·mol^-1. A stable SeO₂ free radical could be formed as O atom with energy surpassing 0.5 eV.