Phonon Spectrum And Thermal Properties Of Carbon Nanotube

The carbon nanotube is a kind of new carbon material. Since it being discovered, the carbon nanotube has become the focus of research. Because the lattice vibration importantly affects the physical property of material on mechanics, heat and light and electricity, therefore the research of carbon nanotube phonon spectrum is extremely important for its physical property.There was several kinds of methods to calculate carbon nanotube's phonon spectrum and the vibrate density of states. Now dynamics simulation software is commonly used. Molecular dynamic simulation is relatively simple and accurate. In 1998, Saito used the force constant model to calculate the phonon spectrum of carbon nanotube by introducing one force constant matrix; this method completely obtained the vibration patterns of carbon nanotube. The result agrees well with the experimental results which obtained by measuring Raman spectrum. But its complex revolutional operation made constructing dynamics matrix so complicated. In this article, we use a set of simple and effective revolve operation that carries translation and revolution operation by using a pair of atoms. This method greatly simplified the computation of dynamics matrix and conveniently calculates the phonon spectrum and the vibration density of states for different types of carbon nanotube.Due to carbon nanotube's application in the nanodevice, the research of carbon nanotube's heat characteristic is important. But these research was just started, and the experimental results was also limited. In the 5th chapter of this article, based on the research on phonon spectrum and the vibration density of states we thoroughly studied the specific heat and heat conductivity varing with the temperature for SWCNT.In recent years, the double wall carbon nonotube(DWCNT) has also been the aroused research interst. In 6th chapter of this article, we studied computation method for the double wall carbon nanotube phonon spectrum and analysed its thermal characters.