C~nSi(n=28,29)各种可能结构的理论研究

利用量子化学从头计算方法研究了C~nSi(n=28,29)各种可能的结构,研究结果表明:C~2~9Si为硅取代碳笼(Fullerens)中一个碳原子而形成的骨0架硅杂碳笼(Fullerenes),而且C~2~9Si最稳定结构是通过硅取代碳笼(C~3~0)最稳定结构中一个碳原子而得到.C~2~9Si比C~3~0有较低的稳定性和较高的化学活性.C~2~8Si有两种类型结构:(I)外接,(Ⅱ)缺位(hole-defect)型,即硅四连接型.计算结果表明,对C~2~8Si,外接硅型化合物更稳定,即(I)为主要成份.而且C~2~8Si最稳定结构是由C~2~8最稳定结构外接硅而形成.计算结果与实验观测一致。

Theoretical studies of various possible structures of C~nSi(n=28,29)

The possible structures of C~nSi (n=28,29) are studied by using ab initio method. Our studies show that C~2~9Si has a closed-cage structure with the silicon atom incorporated into the carbon network, and the most stable structure of C~2~9Si is related to the most stable strucrure of C~3~0 fullerene. C~2~9Si has lower stabilityand higher chemical activity than the C~3~0 fullerene.For C~2~8Si,there are two kindsof structures, namely,(Ⅰ)exohedral and (Ⅱ)hole-defect (the silicon atom is connected to four carbon atoms). Our calculated results show that,forC~2~8Si,the exohedral complexes are more stabl,i. e.,complexes(Ⅰ) are the main ingredient,and the most stable structure of C~2~8Si is formed by the most stable C~2~8 fullerene with an exohedral silicon atom. Our calculated results are in agreement with the experimental ones.