Si团簇的结构特性研究

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.

The study of structural properties for Si clusters

Using the nonorthogonal tight-binding scheme,combined with a genetic algorithm and a molecular-dynamics, we obtain the geometry of the lowest energy for Sin(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 Δ2E, the energy gap of HOMO and LUMO Eg. 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, Sin(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.