Investigation of doping effects on physical properties of carbon nanotubes

We prepared the contents of this thesis in three stages. The first stage, we examined the single-walled carbon nanotubes geometric structures and how they were obtained. The second stage, we examined the electronic band structures, total density of states and electron density of some the graphene and nanotubes which we selected according to the geometric structures, using density functional theory (DFT) and ab-initio pseudo-potential method. In the last stage, we observed the doping effects on a nanotube which we selected.We used the zigzag (6, 0), zigzag (7, 0) chiral (6, 2), chiral (6, 3) and armchair (7, 7) graphene and carbon nanotubes. The first stage, we prepared a program which we will obtain this nanotubes. We obtained the elektronic properties of this graphene and carbon nanotubes and examined the effect of rolling from graphene to nanotubes. In our calculations, we found that zigzag (6, 0) nanotube show matallic behavior. We changed the chiral vector of zigzag (6, 0) and obtained the zigzag (7, 0) nanotube which shows simiconductor behavior and have energy gap and has Eg = 0,5022 eV band gap. We obtained the armchair (7, 7) carbon nanotube which shows matallic behavior. We found that chiral (6, 2) carbon nanotube is a semiconductor and has Eg = 0,8291 eV band gap. We obtained a low band gap for chiral (6, 3) carbon nanotube which is a quasimetallic carbon nanotube. Finally, we found that the bor and beryllium increase the conductivity property of carbon nanotubes. The nitrogen, oxygen and chlorine decrease the conductivity property of carbon nanotubes. The silicon is not changed the conductivity property of nanotube.