Theovetical Study of Silicon Clusters and Metal-Containing Carbon Clusters

1.硅团簇和含硅碳团簇对于Si_n（n=1-20）和SiC_n（n=2-5）团簇，研究了团簇的结构和电子态随团簇尺寸（n）的变化.含过渡金属原子的球形碳团簇（1）研究了金属原子在空心碳团簇（富勒烯）中的包封情况，揭示了其有趣的性质。通过对M@C_<82>、Sc_2@C_<84>和M_2@C_的理论计算<80>，（M=Sc、Y、La、Ce、Pr、Eu、Gd、Yb和Lu），已经公开了以下内容;（a）电子态强烈地依赖于包封金属原子的种类，（B）两个或三个电子从金属转移到碳笼中，（c）金属上的净电荷即使增加或去除一个电子也几乎没有变化，内嵌金属富勒烯被认为是一种“超原子”，（d）内嵌金属富勒烯可以作为更强的电子受体和电子供体;（e）内嵌金属掺杂导致了与空壳的反应性显著不同的有趣的反应性。Sc_2@C_1和La_2@C_1的首次结构测定<84><80>特别值得注意，因为它为生长机制提供了新的见解。有人建议，在最终的退火过程中确定的结构和能量稳定的异构体与一个大的HOMO-LUMO间隙是最丰富的生产和提取。(2)为了揭示金属包埋的动力学行为，对Sc_2@C_2<84>和La_2@C_2<80>进行了详细的研究。发现即使在室温下，两个Sc原子也以相当大的振幅振荡，而两个La原子则以高速循环。两个La^&lt;3+&gt;原子的圆周运动也已经通过观察^<13>C和^<139>La NMR谱进行了实验，并有望提供具有新的电子和磁性的有趣的分子器件。

1. Silicon clusters and silicon-containing carbon clustersFor the Si_n (n=1-20) and SiC_n (n=2-5) clusters, it has been investigated how the structures and electronic states change as the size (n) increases.2. Spherical carbon clusters containing transition metal atoms(1) Encapsulation of metal atoms insides hollow carbon clusters (fullerenes) has been investigated in order to disclose the interesting properties. Through the theoretical calculations of M@C_<82>, Sc_2 @C_<84>, and M_2 @C_<80> (M=Sc, Y,La, Ce, Pr, Eu, Gd, Yb, and Lu), the following has been disclosed ; (a) the electronic sates depend strongly on the kind of encapsulated metal atoms, (b) two or three electrons are transferred from metals to carbon cages, (c) the net charge on metals are little changed even when an electron is added or removed, endohedral metallofullerene being regarded as a sort of "superatom" , (d) endohedralmetallofullerene can act as stronger electron acceptors and donors, and (e) endohedral metaldoping leads to interesting reactivities which differ significantly from those of the empty cases. The first structural determination of Sc_2 @C_<84> and La_2 @C_<80> is especially noteworthy since it provides new insight into the growth mechanism. It has been suggested that the structures are determined during the final annealing process and energetically stable isomers with a large HOMO-LUMO gap are most abundantly produced and extracted.(2) To disclose the dynamic behavior of entrapped metals, Sc_2 @C_<84> and La_2 @C_<80> have been investigated in detail. It has been found that the two Sc atoms are oscillating with considerable amplitude while the two La atoms are circulating at high speed even at room temperature. The circular motion of two La^<3+> atoms has also been experimentally by observing the ^<13>C and ^<139>La NMR spectra and is expected to provide an interesting molecular device with new electronic and magnetic properties.