Carbon nanotubes have attracted much attention for their many promising properties and potential applications. The carbon nanotubes have special structure and excelent physical properties, such as high aspect ratio, high surface area, small size et al, so they own potential applications in many fileds.In this paper, first-principles calculations based on the generalized gradient approximation(GGA) are carried out on the optical properties of zigzag SWNTs from (7,0) to (18,0) and part of DWCNTs, photoelectric absorption properties in wave length from 50nm to 1000nm are obtained.This thesis is organized as below:Chapter 1 reviewed the discovery, preparation, physical properties of single-walled carbon nanotubes and double-walled carbon nano tubes.Chapter 2 gave basic concepts of single-walled carbon nanotubes and double-walled carbon nanotubes, especially in geometrical models and parameters.Chapter 3 introduced the density function theory(DFT) and first-prineiple.Chapter 4 the Perdew Burke Ernzerhof (PBE) method which is included in the density functional theory based on generalized gradient approximation is adopted to calculate the energy band and density of state of zigzag SWCNTs and DWCNTs.The different electronic characteristics are found by comparison between the SWCNTs and the DWCNTs.Chapter 5 the Perdew Burke Ernzerhof method included in the density functional theory based on generalized gradient approximation is adopted to calculate photoelectric properties of zigzag SWCNT (from (7,0) to (18,0)) from the ultraviolet to the infrared band when the polarized and unpolarized electric fields appear. the peak value of optical constants changes with n, and the corresponding wave length of peak value of optical constants changes with n are obtained.Chapter 6 first-principles calculations within the generalized gradient aproximation are carried out on the electromagnetic wave absorption feature of double-walled carbon nanotubes, the electromagnetic wave absorption properties of three kinds DWCNTs in polarized and unpolarized conditions are obtained.Chapter 7 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.
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