Si团簇的结构特性研究

The study of structural properties for Si clusters

采用由M.Menon等人的非正交紧束缚模型,结合遗传算法和分子动力学方法,对n=2～20的中小尺寸Si团簇的结构进行了优化,计算了束缚能Eb、平均配位数CN,团簇的裂化能Efrag,总能的二阶差分Δ2E,最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)的能隙Eg,结合Mullikon集居数分析研究了电子特性,得出了随着团簇尺寸的增加,团簇的构型发生了近球形 长椭球形 近球形的转变、n=4,7,10等团簇具有较强稳定性、团簇中原子之间共价键性结合占支配地位等主要结论。所得的主要结论与已有的从头计算和实验结果相一致。

Using the nonorthogonal tight-binding scheme,combined with a genetic algorithm and a molecular-dynamics, we obtain the geometry of the lowest energy for Si_n(n=2～20)?clusters, and calculate the binding energy E_b per atom, average coordination numbers CN, fragmentation energy E_(frag), the second difference of total energy Δ_2E, the energy gap of HOMO and LUMO E_g. Through analyzing the properties of electrons with use of Mullikon method, we draw the following conclusions: as the increase of cluster size, the geometry 'near spherical-prolate-near spherical' transition occur, Si_n(n=4,7,10)?clusters are the most stable, the bonding between atoms are dominated by covalency. These conclusions are in good agreement with ab initio calculations and experiments.