S4分子结构和振动光谱的从头算

利用量子化学的从头算方法, 在6-311+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/6-311+G^**优化的几何结构基础上, 分别在MP4/6-311+G ^**和QCISD(T)/6-311+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C_2v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.

A Theoretical Study on Structure and Vibrational Spectra of S4

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.