S_4分子结构和振动光谱的从头算

A Theoretical Study on Structure and Vibrational Spectra of S_4

利用量子化学的从头算方法 ,在 6 31 1 +G 基组下 ,分别应用HF ,MP2 ,BLYP ,B3LYP方法优化各种可能的S4分子构型 ,计算各构型的振动光谱 ,并在HF 6 31 1 +G 优化的几何结构基础上 ,分别在MP4 6 31 1 +G 和QCISD(T) 6 31 1 +G 水平上考虑相关能修正对总能量的影响 .比较各种方法计算的几何结构的差别和各构型的相对稳定性 ,得出顺式平面C2v对称构型为基态的结论 .计算表明 ,确定该类分子的基态构型必须考虑电子关联效应的影响 ,B3LYP是计算该类分子既经济又实用的方法 .

The geometric structures of the eight kinds of configurations of S 4 have been optimized by using SCF HF ab initio , MP2 and two density functional methods (BLYP, B3LYP) with 6 311+G ** basis set. Vibrational spectra have been computed for each configuration respectively by HF and B3LYP methods. Total energies have been calculated with the MP4/6 311+G ** and the QCISD(T)/6 311+G ** levels for electron correlation effects using HF/6 311+G ** geometries. The relative stabilities of the different configurations are compared to each other. It is concluded that S 4 has a cis planar C 2v ground state strcture.