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dc.contributor.authorKoberidze, Manana
dc.date.accessioned2012-01-24T20:20:53Z
dc.date.available2012-01-24T20:20:53Z
dc.date.issued2010
dc.identifier.otheroai:jykdok.linneanet.fi:1192640
dc.identifier.urihttps://jyx.jyu.fi/handle/123456789/37243
dc.description.abstractCurrent 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.extent48 sivua
dc.language.isoeng
dc.rightsThis publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.en
dc.rightsJulkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.fi
dc.subject.othersingle-walled carbon nanotube
dc.subject.otherdensity-functional tight-binding
dc.subject.othershear modulus
dc.subject.othergraphene
dc.subject.othervacancy
dc.titleComputational studies of torsional properties of single-walled carbon nanotubes
dc.identifier.urnURN:NBN:fi:jyu-201201241066
dc.type.dcmitypeTexten
dc.type.ontasotPro gradufi
dc.type.ontasotMaster’s thesisen
dc.contributor.tiedekuntaMatemaattis-luonnontieteellinen tiedekuntafi
dc.contributor.tiedekuntaFaculty of Sciencesen
dc.contributor.laitosFysiikan laitosfi
dc.contributor.laitosDepartment of Physicsen
dc.contributor.yliopistoUniversity of Jyväskyläen
dc.contributor.yliopistoJyväskylän yliopistofi
dc.date.updated2012-01-24T20:20:54Z
dc.rights.accesslevelopenAccessfi
dc.contributor.oppiainekoodi402
dc.subject.ysonanoputket
dc.subject.ysografeeni


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