硅纳米管结构和电子性质的第一性原理研究

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(5,0)和(5,5)硅纳米管结构和电子性质。计算结果表明:(5,0)管硅原子相邻键长波动范围为0.068 nm,大于(5,5)管的0.006 nm;通过对(5,0)管的分波态密度进行分析发现,其3s电子和2p电子能量分布在-13～3 eV,但2p电子集中分布在能量较高的-6～3 eV,出现了明显的sp3轨道杂化。同时对(5,0)和(5,5)硅纳米管最高占据轨道和最低未占据轨道的能隙进行了分析,发现两种管导电性能与结构的手性相关,锯齿型(5,0)管能带交叠具有明显的金属性,而扶手型(5,5)管能隙为0.151 eV是半导体纳米管。

First Principle Study on the Structure and Electronic Property of Si Nanotubes

Using the first principles method based on density function theory(DFT),the structures and electronic properties of(5,0) and(5,5) silicon nanotubes were calculated with the generalized gradient approximation.The calculated results show that the fluctuation range of the bond length of adjacent Si-Si for(5,0) tube is 0.068 nm more than 0.006 nm of(5,5) tube.The partial density of states for(5,0) tube was analyzed.And it is found that the 3s and 2p electrons of(5,0) tube are distributed in the region from-13 to 3 eV,but the 2p electron is concentrated in the higher energy region from-6 to 3 eV,and sp3 orbital hybridization is ob-vious.Meanwhile,the energy gaps of the highest occupied molecular orbital and the lowest unoccupied molecular orbital for(5,0) and(5,5) silicon nanotubes were analyzed.And it is found that the conductivity of the two silicon nanotubes is associated with their chiralities,the zigzag(5,0) nanotubes have the obvious metallicity due to the overlapping of their energy gaps,and the armchair(5,5) nanotubes are semiconductor nanotubes with the energy gaps of 0.151 eV.