| Microscopic matter problem attracts researchers'attention more and more because it has different rules from macroscopic one. Therefore,it needs to be studied further to bui1d corresponding theories. In the microscopic matter,nanomatter is typical. The property of nanoclusters, whose sizes are between molecules and crystalsis, is the transition from the microscopic to the macroscopic with the quantitative growth of particles. Studying the change of structures and properties of them on me1ting is crucial to understand the process of the structura1development and to make nanomatteria1. In addition, carbon nanotubues (CNT), as new type nanostructure materials, are very important in the field of nanoscience and nanotechnology because of their unique properties compared to corresponding bulk materials. Carbon nanotubues is the microporous material. The open-ended CNT can be used as the nano-chemical test-tube, siphon, gas storage material and nano-devices, etc. Therefore, the investigation on the formation mechanism of endohedral complexes in CNT has special theoretic meaning, which can open out the physical chemistry property and mechanism of hydrogen storage. It can accelerate the exploitation of the gas storage material and nano-devices. The actual worthiness can not be underestimated.At present, to a great extent the understanding and investigation of CNT in experiment are limited by its nano-scale size, the complicated testing method and the costly testing device. So the computer simulation and the simple physical model help us not only to understand and interpret the experiments at the microscopic level, but also to study regions which are not accessible experimentally, and can give a deep insight into their intrinsic forming mechanism. In this thesis, based on the molecular dynamics (MD) simulations, we studied the melting behavior of Nin clusters (n=20-150) and the dynamics process of rare-gas atoms (He, Ne, Ar, Kr, Xe) injected into single-wall carbon nanotube (SWCNT). The contents of the paper are listed as followed. In Chapter I, we introduce the background knowledge of atomic clusters and the CNTs as well as their possible applications.In Chapter II, we introduce basic principle of molecular dynamics simulations, including building the model potential, potential truncation, short-range interaction computations, integration methods, control methods of macro character and so on. Then, the potential function used is expatiated.In Chapter III, we simulated the melting behavior of Nin clusters (n=20-150) and analyzed their mechanisms of phase transitions using a quantum corrected Sutton-Chen (Q-SC) many-body potential. It turns out that the melting process is not only size-dependent but also a ground state configuration effect. Diverse transitions of ground-state direct the whole melting process at the beginning of heating. A solid-solid transition emerges for Ni28 below melting temperature; Ni29 undergoes a glass transition; Ni55 exhibits solid-liquid melting spreading over a very wide temperature interval, accompanied with the melting of solid-like of core. Direct melting for Nin (n=71, 73, 75) and surface melting for clusters around N=147 have been also observed. Further, some interesting phenomenon has been revealed by comparing the heat capacity curves in the neighborhood of Ni55 and Ni147 both with icosahedral structures, respectively.In Chapter IV, the dynamical processes of Ne atom injected into single-wall carbon nanotube (SWCNT) are modeled by means of Lennard-Jones(LJ) and Kr-C potential, which demonstrates the encapsulated rare-gas atoms can constantly oscillating in SWCNT with the appropriate tube radius and threshold energies. Also, it is revealed that the nanotube length, diameter and chirality can be used to tune the oscillation.Finally the main points of the thesis are summarized and the prospective researches are discussed. |
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