Structural and electronic properties of carbon-based materials
Author(s)
Advisor
Çıracı, SalimDate
2000Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
In this thesis, some carbon-based materials in nano scale have been investigated
by using first-principles methods as well as transferable tight-binding and
empirical potential models. The focus of interest has been in the cubane molecule
among cage-like structures and in the carbon nanotubes among graphite-related
materials. The first-principles calculations predict that cubane-like structures
can exist for other group IV elements such as Si and Ge. The energetics and
dynamics of such molecules has been studied. By performing quantum molecular
dynamics simulations at high temperature a deformation path from cubane to
cyclooctatetraene has been established. For solid cubane the structural and
electronic properties and doping by alkali metal atoms have been studied. In the
study of carbon nanotubes under pressure some new carbon forms due to covalent
bonding between the neighboring tubes has been identified. It has been shown
that the electronic structure of single wall carbon nanotubes is affected by radial
deformations. For example, some zigzag nanotubes have been found to experience
semiconductor-to-metal transition as a result of compression. Exploiting this
property, it has been shown that variable and reversible quantum structures can be realized on a single carbon nanotube. Finally, other quantum structures which
can lead to novel nano-scale molecular devices have been proposed.
Keywords
Cubane moleculeSolid cubane
Carbon nanotubes
Quantum molecular dynamics
Electronic structure calculations