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 - 2 0的中小尺寸Si团簇的结构进行了优化 ,计算了团簇的束缚能Eb、平均配位数CN ,裂化能Efrag,总能的二阶差分△2 E ,HOMO和LUMO的能隙Eg,得出了随着团簇尺寸的增加 ,构型发生了近球形 -长椭球形 -近球形的转变、n =4,7,1 0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, 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 △_2E , the energy gap of HOMO and LUMO E_ g, 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. The conclusions are in good agreement with ab inition calculation and experiments.