Research On The Electronic And Optical Properties Of Carbon Nanotubes

Diamond and graphite are well-known as two kinds of carbon allotropes which represent the three-dimension and two-dimension atomic distribution in space while fullerenes and carbon nanotubes, founded in 1990s, represent the one-dimension and zero-dimension distribution. With the developing of nanotechnology, carbon nanotubes are widely researched as new materials with their special characters. Some physical properties are detected through experiments, including structure and electronic properties. To obtain more physical properties, it is necessary to calculate and analyze physical properties theoretically by establishing a carbon nanotube model. This thesis analyzes the electronic and a part of optical properties of zigzag carbon nanotubes by using density function theory calculation, and also studies on the changes of these properties with structure deformation.This thesis contains six chapters:Chapter 1 simply introduced the history, macro-physical properties and applications in some areas of carbon nanotubes.Chapter 2 gave basic concepts of carbon nanotubes, especially in geometrical models and parameters.Chapter 3 introduced the density function theory(DFT), including local density approximation(LDA) and generalized gradient approximation(GGA).Chapter 4 firstly calculated the band structure of a set of non-deformation zigzag carbon nanotube using LDA and GGA. The results were compared with each other and also with experimental results, then the relationship between energy gaps and diameters of carbon nanotubes was obtained and the slight differences of GGA and LDA calculation results were also demonstrated; secondly only GGA was used to calculate the band structure of (10,0),(12,0),(13,0),(16,0) with deformation along radial direction and also calculate the band structure of (10,0) with deformation along axial direction, for studying the relationship between band structure and structure deformation; Finally calculated the electronic transport properties of systems containing two-end-capped (6,0) nanotube and atomic lithium electrode using GGA and non-equilibrium Green's function(NEGF).Chapter 5 firstly using GGA calculated the complex dielectric and absorption of a set of non-deformation zigzag carbon nanotube; secondly studied the relationship between complex dielectric, absorption and deformation of (10,0) through GGA calculation.Chapter 6 gave a summary and outlook of this thesis. The main research results and limitation of the thesis were listed and the direction of further research was also pointed out.