| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 91 === In this study, the arc vaporization which makes nanotubes have been simulated by quantum molecular dynamics for different manufacture parameters. Parameters are radius of nanotube, substrate temperature and incident energy of droping atoms.
First, The many body potential functions for intermolecular are described by the tight-binding potential. Following the second law of Newton, the Leap-Frog method is adopted to calculate atom’s physical properties, such as position and velocity, etc. To reduce the computer simulation time, the algorithms of Verlet list and cut-off potential are applied to calculate the interactive force between atoms.
The results of loading :
1. When the radius of tube is getting small, it is easier to form the pentagon from the beginning of growth. And when the radius of tube is getting bigger, it is easier to form the hexagon.
2. No matter how the radius of tube is, when the temperature is getting hotter, it is easier to form the closed-end. This is because when the temperature gets hotter, the vibration frequencies of atoms in the end of the tube would get more quickly. And it would also increase the opportunities to seal the end of the tube.
3. The smaller radius tube of carbon nanotube: When the incident kinetic energy of atoms get larger, it would make a bigger displacement of atoms in the end of the tube; therefore it would shorten the closed-time. But while the incident kinetic energy is much larger, it would affect the binding of the closed-end of atoms and would form the disorder structures. In opposition, atoms in the end of the tube which the bigger radius tube is much stable than the small ones. So incident energy of bigger radius tube which can disturb the cap structure is less than small ones.
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