硅碳纳米管(8, 0)几何结构和电子结构性质密度泛函理论的第一性原理研究

Geometrical and Electronic Structures of (8, 0) SiCNTs: A First-Principles Study

摘要: 本文基于密度泛函理论的第一性原理方法，在广义梯度近似下，研究了硅碳纳米管(8, 0)几何结构和电子结构性质。硅碳纳米管(8, 0)是由32个碳原子和32个硅原子，共计64个原子组成的折叠之字形结构。计算结果表明：硅碳纳米管(8, 0)的相邻原子碳和硅所构成的Si-C键的平均键长为0.1787 nm，平均直径为0.797 nm。对电子结构性质的研究是通过将最高占据轨道和最低未占据轨道的能隙进行了分析，实验中得到能带最高占据轨道跟最低未占据轨道为1.344 eV，并且其能带最高占据轨道跟最低未占据轨道在同一对称点上，因此定性其为直接带隙半导体。通过对硅碳纳米管(8, 0)电子态密度图分析，发现其电子分布的峰值差异较大：电子主要分布在−0.55 eV~0.15 eV之间，其中−0.35 eV~0.3 eV和0.12 eV~0.15 eV之间几乎无电子分布，在−0.15 eV~−0.12 eV之间电子分布最多。通过本计算模拟研究可对今后硅碳纳米管的结构、性能研究及应用发展提供理论参考。

Abstract: In this paper, based on the first principle method of density functional theory, the geometric structure and electronic structure properties of silicon carbon nanotubes (8, 0) are studied under the generalized gradient approximation. Silicon carbon nanotube (8, 0) is a folded structure con-sisting of 32 carbons and 32 silicon atoms, which consist of 64 atoms. The calculated results show that the average bond length of the Si-C bond formed by the adjacent atoms carbon and silicon of silicon carbon nanotubes (8, 0) is 0.1787 nm, and the average diameter is 0.797 nm. The study of the properties of electronic structures is based on the analysis of the energy gap of the highest oc-cupying orbit and the lowest unoccupied orbit. In the experiment, the maximum occupying orbit and the lowest unoccupied orbit are 1.344 eV, and the highest occupying orbit and the lowest un-occupied orbit are at the same symmetry point, so it is qualitatively the direct band gap Semicon-ductor. By analyzing the electron density map of silicon carbon nanotubes (8, 0), it is found that the electron distribution peaks are different: electrons are mainly distributed between −0.55 eV and 0.15 eV, of which there is almost no electron distribution between −0.35 eV to 0.3 eV and 0.12 eV to 0.15 eV, and the most electron distribution is between −0.15 eV and −0.12 eV. The present study will provide theoretical references for the future research and application of silicon nanotubes.