单壁碳纳米管连接结中缺陷移动与修复的分子动力学研究凝聚态物理专业论文.docx

II II Abstract Intramolecular junctions in single-walled carbon nanotubes are potentially ideal structures. Ouyang et al reported that the (22,-5)/(21,-2) and (11,8)/(9,6) junctions had been made in science journal. Hashimoto et al made a SWNT of mixed chirality (17,0)/(18,0) sigle carbon nanotube junction by electron bombardment. Consequently, carbon nanotubes junction exist or be made by radiation. We have used molecular dynamics simulation to study the formation regularity of the junctions between two single-walled carbon nanotubes and the motion and reconstruction of the defect in junctions. Furthermore, we studyed the microscopic mechanism of the motion and reconstruction of these single-walled carbon nanotube junctions. First, employing semiempirical Tersoff potential to describe the C-C interactions in single-walled carbon nanotube junctions, we simulated the formation of the junctions between two adjacency zigzag and adjacency armchair single-walled carbon nanotubes，respectively. The simulation results show that the defects are formed by pentagon-heptagon pairs and there is a pair of pentagon-heptagon in zigzag junctions and a pairs of separate pentagon-heptagon in armchair junctions. These simulation results are in agreement with Hashimoto’: pentagon-heptagon pair is the most probably responsible for the serial junctions of two parts of SWNTs with different chiral indices. Taking (7,0)/(8,0) and (6,6)/(7,7) carbon nanotube junctions for examples, we studyed the thermal stability of single-walled carbon nanotube junctions. The results tell us that the two C located at the two wing of the pentagon-heptagon topological defects with lower remove energy can more easily be evaporated and leave the system. Molecular dynamics calculations are performed to study the dynamics of the movement of the (7,0)/(8,0) and (6,6)/(7,7) junction interconnecting two carbon nanotubes. The experimentally observed complex longitudinal and helical movements of the kink are well repr