Correlated electronic properties of some graphene nanoribbons: A DMRG study

Goli, Durga Prasad VML and Prodhan, Suryoday and Mazumdar, Sumit and Ramasesha, S (2016) Correlated electronic properties of some graphene nanoribbons: A DMRG study. In: PHYSICAL REVIEW B, 94 (3).

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Abstract

The significant electron-electron interactions that characterize the pi 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 pi-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.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	24 Aug 2016 09:11
Last Modified:	24 Aug 2016 09:11
URI:	http://eprints.iisc.ac.in/id/eprint/54459

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