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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/100/14175

Title: Unit cell dependence of optical matrix elements in tight-binding theory: The case of zigzag graphene nanoribbons
Authors: GUNDRA, K
SHUKLA, A
Keywords: GRAPHITE
GAS
Issue Date: 2011
Publisher: ELSEVIER SCIENCE BV
Citation: PHYSICA B-CONDENSED MATTER,406(19)3538-3543
Abstract: In the tight-binding theory, momentum matrix elements (MMEs) needed to calculate the optical properties are normally computed using a formulation based on the gradient of the Hamiltonian in the k space. We demonstrate the inadequacy of this formulation by considering the case of zigzag graphene nanoribbons. We show that one obtains wrong values of MMEs, in violation of the well-known selection rules, if the unit cell chosen in the calculations does not incorporate the symmetries of the bulk. This is in spite of the fact that the band structure is insensitive to the choice of the unit cell. We substantiate our results based on group-theoretic arguments. Our observations will open an avenue for proper formulation of MMEs. (C) 2011 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.physb.2011.06.008
http://dspace.library.iitb.ac.in/jspui/handle/100/14175
ISSN: 0921-4526
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