Constant-Pressure Molecular-Dynamics Study of Carbon Nanotubes and Electronic Structure of New Phases

The pressure-induced structural phase transition of carbon nanotubes is studied using the constant-pressure tight-binding molecular-dynamics method. We find that an interesting sp²–sp³ hybrid structure, which is considered as a graphitic nanoribbon solid, is obtained from the nanotube solid composed of armchair nanotubes. The sp³-rich phase with anisotropic atomic network is also obtained at elevated pressure and is predicted to have high hardness which is comparable to that of cubic diamond. In contrast, the bundle composed of both armchair and chiral nanotubes transforms into amorphous diamond phase at high pressure. From the electronic-structure study in the framework of the density-functional theory, the nanoribbon solid phase obtained is found to be metallic. ©2010

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