紧束缚分子动力学模拟纳米硅管的稳定结构

Tight-binding Molecular Dynamics Simulations:the Structure and Stability of Silicon Nanotubes

利用紧束缚分子动力学退火方法模拟研究了纳米硅管(SiNT)的稳定结构和基态能量,结果表明:几何结构特征对纳米硅管的结合能有重要影响,平均键长为0.236 4 nm,表面为双层原子面,具有很高的亚稳性,锯齿型管比扶手椅型管的原子结合能大0.051 eV/atom,SiNT(m,m)(m=2-4)不具有管状结构,SiNT(2,2)可以作为单元形成硅纳米线.

The structure and stability of silicon nanotubes（SiNTs） are simulated based on the tight-binding molecular dynamics with transferability. It is found that chiral and diameter of SiNTs have an important influence on the cohesive energy, their average bond length is 0. 2364nm, with double layer atom surface. When the different chirality is accounted for, it appears that the zigzag structure is energetically preferred. Remarkably, the SiNT（2,2） may form silicon wire as basic unit. Although SiNTs have been successfully synthesized, there is no doubt that they are highly metastable structures due to the preference of silicon to be sp3 hybridized.