环型硫分子的从头算及其应用

通过对环型硫分子S6～S20同素异构体的实验结构分析,用从头算(ab initio)RHF/6-311G*(包括BLYP/6-311G* 和MP4/6-311G*)方法进行基态几何结构优化,获得了与实验结构相吻合的新的理论稳定构型.其中S18的两种变体S18(α)和S18(β)的能量相近,都是相互稳定的分子构型.通过计算,从理论上推测S20有D4点群的物相.还就对称性、偶极矩和红外振动光谱与分子构象的相互关系,以及环分子结构与化学活性之间的关系进行了讨论,获得了具有实验意义的结论.

The ab initio Studies on the Structures of Cyclic Sulfur and Their Applications

The ground state geometrical optimizations of cyclic sulfur molecules S6~S20 have been studied with RHF/6-311G* and MP4/6-311G* ab initio methods, and are in agreement with the experimental conformations. The stable molecular structures of recent S14both experimental and theoretical are Cs symmetry and the bond parameters of optimizations are very close to those of experiments. S18(α) and S18(β) are two types of modification of S18ringwhich have been proved of the same stability due to their close energies. The polymorphic phase S20 of D4 point group has also been proved by calculating the structures and comparing the relative energies of D4with that of D2. Otherwise, The relationships of molecular conformation models with symmetries, dipole moments and vibrational frequencies have been discussed. The significant applications of cyclic sulfur have been deduced by studyingthe relations between their electronic structures and chemical reactivities.