手性型硅纳米管的核生长与电子特性研究

发布时间：2018-05-29 10:42

本文选题：手性型硅纳米管 + 密度泛函　；参考：《新疆师范大学》2017年硕士论文

【摘要】：通过密度泛函理论,对手性型硅纳米管核团簇的几何构型、核团簇衍生过程以及无限长的手性型单、双、三壁硅纳米管的电子特性进行了研究。详细描述了研究的主要过程。首先描述手性型硅纳米管核团簇的几何构型;其次,研究核团簇的衍生规律,经分析得出由核团簇生长为手性型硅纳米管是通过逐层生长的方式进行的;接着通过手性型硅纳米团簇的结合能,进一步分析稳定性与生长趋势,经分析表明手性型硅纳米团簇的稳定性随着长度和管径的增加而增加,说明能够得到手性型硅纳米管;最后利用周期性边界条件,得到无限长手性型硅纳米管的结构,并通过结合能、能带以及电子态密度研究其稳定性与电子特性。经分析表明:(1)手性型单壁硅纳米管(n,n/2)的稳定性随着直径增加逐渐增强;手性型双壁硅纳米管(n,n/2)@(2n,n)的稳定性随着直径的增加与管间距的增加逐渐增强;手性双壁硅纳米管(2n,n)@(3n,3n/2)的稳定性随着直径的减少与管间距的增加逐渐增强。(2)对单壁手性型硅纳米管来说,若手性指数都是3的整数倍,则具有金属性质;当手性指数不是3的整数倍,则具有半导体性质,并且随着管径的增加带隙逐渐减小。特别地,对管径非常小的手性型硅纳米管来说,由于曲率效应会出现反常。例如手性指数为(4,2)和(6,3)的手性型硅纳米管。双壁、三壁手性型硅纳米管与单壁手性型硅纳米管的规律相同,即双壁手性型硅纳米管两个壁的手性指数都是3的倍数或三壁手性型硅纳米管三个壁的手性指数都是3的倍数,则具有金属性质,否则具有半导体性质。特别地,双壁手性型硅纳米管(4,2)@(8,4),三壁手性型硅纳米管(4,2)@(8,4)@(12,6)由于曲率效应出现反常。此次研究是首次对手性型硅纳米管进行理论研究,可作为一个前期理论与方法的探索和积累,为实验研究提供一个思路、方向,为之后的研究进行铺垫和探索。
[Abstract]:The electronic properties of chiral silicon nanotubes were investigated by density functional theory (DFT), the geometric configuration of chiral silicon nanotubes, the derivation process of the clusters and the electronic properties of infinite chiral single, double and three-walled silicon nanotubes. The main process of the research is described in detail. Firstly, the geometric configuration of chiral silicon nanotube clusters is described. Secondly, the derivation law of the clusters is studied, and it is concluded that the growth of chiral silicon nanotubes from the clusters is carried out layer by layer. Then the stability and growth trend of chiral silicon nanoclusters were analyzed through the binding energy of chiral silicon nanoclusters. The results showed that the stability of chiral silicon nanoclusters increased with the increase of length and tube diameter, indicating that chiral silicon nanotubes could be obtained. Finally, the structure of infinite chiral silicon nanotubes is obtained by using periodic boundary conditions. The stability and electronic properties of the nanotubes are studied by means of binding energy, band and electron density of state. The results show that the stability of chiral single-walled silicon nanotubes increases with the increase of diameter, and the stability of chiral double-walled silicon nanotubes increases with the increase of diameter and spacing. The stability of chiral double-walled silicon nanotubes with 3nnnn-1 / 2) increases with the decrease of diameters and the increase of the distance between tubes. (2) for single-walled chiral silicon nanotubes, if the chirality index is 3 times, the chiral properties of the chiral nanotubes are metallic. When the chiral index is not an integral multiple of 3, it has semiconductor properties, and the band gap decreases with the increase of the diameter of the tube. In particular, for chiral silicon nanotubes with very small diameters, anomalies occur due to the curvature effect. For example, chiral silicon nanotubes with chiral index of 4 ~ 2) and 6 ~ 6 ~ 3). The chiral index of double wall chiral silicon nanotubes and single wall chiral silicon nanotubes is the same as that of single wall chiral silicon nanotubes, that is, the chirality index of two walls of double wall chiral silicon nanotubes is a multiple of 3, or the chirality index of three walls of three wall chiral silicon nanotubes is a multiple of 3. It has metal property, otherwise it has semiconductor property. In particular, the double walled chiral silicon nanotubes have an anomaly due to the curvature effect. This study is the first theoretical study of chiral silicon nanotubes, which can be used as a preliminary theory and method to explore and accumulate, to provide a train of thought for experimental research, and to pave the way for future research.
【学位授予单位】：新疆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O469

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