中等正离子硅团簇的稳定结构及结构演变

用全势能线性muffin-tin轨道分子动力学（FP-LMTO-MD）方法与单亲基因进化算法相结合，对正离子Si11-30团簇的几何结构和电子结构进行了研究。对于正离子Si11-20团簇，结果与以前报道的相一致，但发现了一些与基态结构几乎一样稳定的同质异构体结构。特别是用上述方法找到了正离子Si21-30团簇的基态结构。尽管这些基态结构很可能与中性团簇的不同，但是它们大部分与中性团簇一样含有三帽三棱柱（TTP）子单元结构。当n〈25时，正离子团簇的长形结构比球状结构稳定，当n=25时，致密的球形结构比长形结构稳定，但当n=26和27时，球形结构与长形结构的稳定性发生逆转，而结构真正转化的大小发生在n=28。

Stable Structures and Structural Evolution of Medium- size Silicon Cluster Cations

The geometric and electronic structures of cationic Si_(11-30) clusters have been investigated by using full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO-MD) method based on single-parent evolution algorithm. For cationic Si_(11-20) clusters, our results are in agreement with those reported previously. But, some isoenergetic isomers with the ground state structures have been found. In special, we have found the ground state structures for cationic Si_(21-30) clusters using FP-LMTO-MD based on single-parent evolution method. Although the ground state structures for the cations are probably different from those for the neutrals, most of the lowest energy structures for the cations include a sub-unit of tricapped trigonal prism (TTP) as the neutrals. When n<25,the prolate structures of the cations are more stable than the compact structures. When n=25, a compacted structure is the ground state structure for Si~+_(25). However, for the cationic silicon clusters with n=26 and 27, the prolate structures are more stable than the compact structures again. The second structural transition size occurs at n=28.