SF_5CF_3几何构型及红外振动光谱的量子化学研究

Quantum-Chemical Studies on Geometrical Structure and IR Harmonic Vibrarional Spectrum of SF_5CF_3

采用8种密度泛函方法BHLYP,BLYP,B3LYP,BP86,B3P86,B3PW91,BPW91和KMLYP,以及DZP++基组,对新的温室气体SF5CF3进行了几何构型优化和红外谐振光谱计算.该分子为Cs构型.通过计算值与实验值比较,用KMLYP和BHLYP方法所得几何构型参数与实验值最接近.采用8种方法对SF5CF3进行了红外谐振频率计算,通过与实验值对比,用B3LYP,B3P86和B3PW91方法得出了比较满意的结果.其平均绝对误差分别为29cm-1,22cm-1和24cm-1.红外吸收强度预测表明,SF5CF3是一种威胁性很大的温室气体.

Density functional methods BHLYP, BLYP, B3LYP, BP86, B3P86, B3PW91, BPW91 and KMLYP were carried out to study the geometrical structure and IR harmonic vibrarional spectrum of SF_5CF_3, a new greenhouse gas. The DZP^(++) basis sets were employed. The optimized molecule geometry has C_s symmetry. Compared with experimental data, the geometrical parameters optimized with KMLYP/DZP^(++) and BHLYP/DZP^(++) methods are closer to the experimental value. B3LYP, B3P86, and B3PW91 methods give the better IR spectrum predictions for SF_5CF_3. The average absolute errors are 29 cm^(-1), 22 cm^(-1), and 24 cm^(-1) respectively. The prediction of IR absorption intensity shows that SF_5CF_3 is a very effective greenhouse gas with the potential for a significant impact on global warming considerations.