SeO_x(x=1,2)的从头算势能曲线和光谱常数

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

采用从头算的多种方法和基组优化计算SeOx(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.

Possible ground state structures, harmonic frequency and dissociation energy of SeOx（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 SeOx（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.