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Nonlocal exchange interaction removes half-metallicity in graphene nanoribbons
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
KTH, School of Biotechnology (BIO), Theoretical Chemistry.ORCID iD: 0000-0003-0007-0394
2007 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 7, no 8, 2211-2213 p.Article in journal (Refereed) Published
Abstract [en]

Band gap studies of zigzag-edge graphene ribbons are presented. While earlier calculations at LDA level show that zigzag-edge graphene ribbons become half-metallic when cross-ribbon electric fields are applied, our calculations with hybrid density functional demonstrate that finite graphene ribbons behave as half-semiconductors. The spin-dependent band gap can be changed in a wide range, making possible many applications in spintronics.

Place, publisher, year, edition, pages
2007. Vol. 7, no 8, 2211-2213 p.
Keyword [en]
Electric fields; Energy gap; Ion exchange; Molecular interactions; Semiconductor materials; Graphenes; Nanoribbons; Nonlocal exchange; Zigzag-edge graphene; Nanostructures; carbon; nanotube
National Category
Theoretical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-7740DOI: 10.1021/nl070593cISI: 000248657800008PubMedID: 17602536Scopus ID: 2-s2.0-34548168661OAI: oai:DiVA.org:kth-7740DiVA: diva2:12857
Note
QC 20100817Available from: 2007-12-04 Created: 2007-12-04 Last updated: 2010-08-17Bibliographically approved
In thesis
1. Quantum Chemistry for Large Systems
Open this publication in new window or tab >>Quantum Chemistry for Large Systems
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis deals with quantum chemistry methods for large systems. In particular, the thesis focuses on the efficient construction of the Coulomb and exchange matrices which are important parts of the Fock matrix in Hartree-Fock calculations. Density matrix purification, which is a method used to construct the density matrix for a given Fock matrix, is also discussed.

The methods described are not only applicable in the Hartree-Fock case, but also in Kohn-Sham Density Functional Theory calculations, where the Coulomb and exchange matrices are parts of the Kohn-Sham matrix. Screening techniques for reducing the computational complexity of both Coulomb and exchange computations are discussed, including the fast multipole method, used for efficient computation of the Coulomb matrix.

The thesis also discusses how sparsity in the matrices occurring in Hartree-Fock and Kohn-Sham Density Functional Theory calculations can be used to achieve more efficient storage of matrices as well as more efficient operations on them.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. xi, 56 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2007:13
Keyword
quantum chemistry, fast multipole method, density matrix purification, sparse matrices
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-4561 (URN)978-91-7178-797-2 (ISBN)
Public defence
2007-12-12, FA32, Albanova, Roslagstullsbacken 21, 106 91 Stockholm, 13:00
Opponent
Supervisors
Note
QC 20100817Available from: 2007-12-04 Created: 2007-12-04 Last updated: 2010-08-17Bibliographically approved

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Luo, Yi

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