小分子硫原子团簇的结构稳定性

Structural Stabilities of Small Sulfur Clusters

用分子图形软件设计出68种硫原子团簇S_3～S_(13)的结构，使用B3LYP密度泛函进行几何构型优化和振动频率计算，排除了振动频率为负值的非局域极小点的结构，根据分子的总能量得出最稳定的同分异构体。在硫原子团簇中，除了部分原子采用一、三配位之外，大部分原子为二配位成键，带三配位的硫原子团簇的总能量较高，硫原子团簇难以生成高配位的笼状结构。从S_5开始链状结构能量高于环状，中性大分子硫原子团簇多呈链状结构。

We acquired 68 small sulfar clusters from S-3 to S-13 with molecular graphics and then carried out the optimizations and vibrational frequencies by density functional calculations. The non-minimum structures with negative vibrational frequencies were excluded. When designing these isomers, the sulfur atoms could be in one-fold, two-fold and three-fold. The sulfur clusters with three-fold atom are higher in energies. It is rare to form a cage structure with multi-fold atom(s). By comparing the total energies of the different isomers, the energies of ring structures are higher than those of chain ones from S-5. The large neutral sulfur clusters are mostly ring structures.