Computational studies of torsional properties of single-walled carbon nanotubes

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Show simple item record Koberidze, Manana 2012-01-24T20:20:53Z 2012-01-24T20:20:53Z 2010
dc.identifier.uri en
dc.description.abstract Current thesis presents computational studies of the torsional twist in single walled carbon nanotubes (SWCNTs). Since SWCNTs can be viewed as rolled up graphene sheets, our aim is to explain their torsion constants via shear mod- ulus of graphene in pristine, and single- and double vacancy cases. In addition, fundamental energy gap response to torsion is investigated. Calculations of defected structures is computationally expensive as it requires larger simula- tion cell with large number of atoms. To reduce the cost of computations we take the advantage of chiral symmetry of nanotubes instead of translational one, and faster performance of density-functional tight-binding method compared to other computational methods. Shear modulus calculations show that its value approaches that of graphene for large diameter tubes and is most sensitive to size in case of armchair tubes. Vacancies diminish shear modulus for most of the nanotubes and concentration-induced decrease has linear character regardless of chirality. Studies on direction-dependent shearing of graphene reveals that in the presence of double vacancy shear modulus has the biggest fluctuations from its average value compared to pristine and single vacancy instances. Torsion significantly modifies electronic structure as well - metallic tubes undergo tran- sition to semiconducting state, during which band gap change is linear, peaking and decreasing to zero again for most of the tubes. Results give the ground for assumption that for large diameter tubes the peak values, reached during torsion, converge.
dc.format.extent 48 sivua
dc.language.iso eng
dc.rights This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. en
dc.rights Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. fi
dc.rights openAccess fi
dc.subject.other single-walled carbon nanotube
dc.subject.other density-functional tight-binding
dc.subject.other shear modulus
dc.subject.other graphene
dc.subject.other vacancy
dc.title Computational studies of torsional properties of single-walled carbon nanotubes
dc.identifier.urn URN:NBN:fi:jyu-201201241066
dc.subject.ysa nanoputket
dc.subject.ysa grafeeni
dc.type.dcmitype Text en
dc.type.ontasot Pro gradu fi
dc.type.ontasot Master’s thesis en
dc.contributor.tiedekunta matemaattis-luonnontieteellinen tiedekunta fi
dc.contributor.tiedekunta Faculty of Sciences en
dc.contributor.laitos fysiikan laitos fi
dc.contributor.laitos Department of Physics en
dc.contributor.yliopisto University of Jyväskylä en
dc.contributor.yliopisto Jyväskylän yliopisto fi 2012-01-24T20:20:54Z

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