Tight binding molecular dynamics simulation of carbon nanotubes

In the first part of the thesis, the variation of the structural stability, physical characteristics andthe energetics of the (10,10) Single-Walled Carbon Nanotubes (SWCNT?s) with respect totemperature and the structural deformations at high temperatures have been investigated by usingO(N) Tight Binding Molecular Dynamics (TBMD) simulation method. As the temperatureincreases some deformations have been observed along the axis of the tube, while the structure isobserved to sustain its stability up to high temperatures. As the temperature increases the totalenergy per atom increases linearly and the tube expands radially. Above simulation temperaturesof around 2000K, carbon atoms are observed to start to detach from the tube and therefore thehexagonal structure started to disintegrate. The effects of the heating method and the electronictemperature on the results have been examined.In the second part of the thesis, the effect of temperature on the tensile strength and themechanical properties of CNT?s are investigated under uniaxial strain. It is observed that CNT?sbecome more sensitive to tension due to an increase in temperature and the disintegration ofatoms from their places is possible at lower strain values with the increasing temperature.However, it is shown that CNT?s do not have high strength under compression and the increaseof temperature does not affect this strain value. The stress-strain curves of CNT?s weredetermined. The elastic limit, Young?s modulus and tensile strength of the tube were calculatedfrom these curves. Poisson ratio was also calculated and the effect of temperature on theseparameters has been examined.Keywords: Carbon nanotube, O(N) tight binding, molecular dynamics simulation, temperature,stability, strength, strain, stress, mechanical properties.JURY:1. Prof. Dr. Gülay DERELİ (Supervisor) Date: 29.06.20062. Prof. Dr. Hasan TATLIPINAR Page: 1263. Prof. Dr. Fatma TEPEHAN4. Assoc. Prof. Dr. Hikmet YÜKSELİCİ5. Prof. Dr. Mine YURTSEVER