Correlated electronic properties of some graphene nanoribbons: A DMRG study

V. M. L. Durga Prasad Goli, Suryoday Prodhan, Sumit Mazumdar, and S. Ramasesha
Phys. Rev. B 94, 035139 – Published 18 July 2016
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Abstract

The significant electron-electron interactions that characterize the π electrons of graphene nanoribbons (GNRs) necessitate going beyond one-electron tight-binding description. Existing theories of electron-electron interactions in GNRs take into account one electron–one hole interactions accurately but miss higher-order effects. We report highly accurate density matrix renormalization group (DMRG) calculations of the ground-state electronic structure, the relative energies of the lowest one-photon versus two-photon excitations, and the charge gaps in three narrow GNRs within the correlated Pariser-Parr-Pople model for π-conjugated systems. We have employed the symmetrized DMRG method to investigate the zigzag nanoribbon 3-ZGNR and two armchair nanoribbons 6-AGNR and 5-AGNR, respectively. We predict bulk magnetization of the ground state of 3-ZGNR, and a large spin gap in 6-AGNR in their respective thermodynamic limits. Nonzero charge gaps and semiconducting behavior, with moderate to large exciting binding energies, are found for all three nanoribbons, in contradiction to the prediction of tight-binding theory. The lowest two-photon gap in 3-ZGNR vanishes in the thermodynamic limit, while this gap is smaller than the one-photon gap in 5-AGNR. However, in 6-AGNR the one-photon gap is smaller than the two-photon gap and it is predicted to be fluorescent.

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  • Received 11 January 2016
  • Revised 23 May 2016

DOI:https://doi.org/10.1103/PhysRevB.94.035139

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

V. M. L. Durga Prasad Goli1,*, Suryoday Prodhan1,†, Sumit Mazumdar2,3,‡, and S. Ramasesha1,§

  • 1Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
  • 2Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
  • 3College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA

  • *durgaprasad.vml@gmail.com
  • suryodayp@sscu.iisc.ernet.in
  • sumit@physics.arizona.edu
  • §ramasesh@sscu.iisc.ernet.in

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Issue

Vol. 94, Iss. 3 — 15 July 2016

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