Correlated electronic properties of some graphene nanoribbons: A DMRG study

V. M.L.Durga Prasad Goli, Suryoday Prodhan, Sumit Mazumdar, S. Ramasesha

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

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.

Original languageEnglish (US)
Article number035139
JournalPhysical Review B
Volume94
Issue number3
DOIs
StatePublished - Jul 18 2016

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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