First Principle Investigations On The Electronic Structures Of Graphene Nanoribbon And Its Interactions With Muonium
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Date
2010-11
Authors
Ang, Lee Sin
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
The results reported here are from the theoretical investigations of the graphene systems. In selecting the suitable methods for use in the simulations, a few methods, ranging from molecular orbital, post-self-consistent field, and density functional theory (in the forms of pure and hybrid functionals) are selected. B3LYP emerged as the suitable choice for use in the investigations as other methods suffer from spin contamination and the problem of efficiency. In order to find the models that are suitable for use in molecular orbitals cluster calculations, two sets of graphene nanoribbon models, one with zigzag and the other the armchair edges were investigated. It was found that the electronic properties and the geometries of the graphene nanoribbons do depend on the size of the graphene nanoribbons. Analysis of molecular orbitals, spin densities, charges and bond lengths of the models show that for a certain size, the electronic properties of the models mimic those of the infinitely long graphene nanoribbons. For the adsorption of muonium on the basal plane of a graphene nanoribbon, the site where the muonium connects directly to the carbon atom is the most stable site. From the analysis of the interactions between muonium and the underlying graphene nanoribbons, LUMO and HOMO of the systems are mostly from the graphene nanoribbons. At the most stable site, the Fermi contact term is 111 MHz for armchair-edged GNR and 129 MHz for zigzag-edged GNR, while the anisotropic couplings are negligible. These findings can be the reference in performing experiment that use muon to identify the type of the edges of a graphene nanoribbons.
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Keywords
The electronic structures of graphene nanoribbon , and its interactions with muonium