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Exciton binding energy in the strong correlation limit of conjugated chains

Shuai, Z and Brédas, JL and Pati, SK and Ramasesha, S (1998) Exciton binding energy in the strong correlation limit of conjugated chains. In: Physical Review B, 58 (23). pp. 15329-15332.

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Official URL: http://prola.aps.org/abstract/PRB/v58/i23/p15329_1


By applying the numerically accurate symmetrized density-matrix renormalization-group method coupled with the extended Hubbard-Peierls model, we find that (i) the on-site Hubbard repulsion energy U dramatically reduces the binding energy of the lowest optically allowed 1B(u) exciton; (ii) in the zero-dimerization limit, there exists a critical value of V at which the 1B(u) exciton becomes bound; the critical value V-c = 2t is fully in agreement with the recent analytical results at the infinite-ii limit by Gallagher and Mazumdar [Phys. Rev. B 56, 15025 (1997)]. Furthermore, this critical value decreases appreciably for weaker on-site correlation strengths, when the dimerization amplitude (delta) is nonzero; The present accurate numerical results contradict those obtained recently by Yu, Saxena, and Bishop [Phys. Rev. B 56, 3697 (1997)] both qualitatively and quantitatively. We also present first-order perturbation plus random-phase-approximation and single configuration-interaction analyses to rationalize the numerical calculations.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: Copyright of this article belongs to American Physical Society.
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 19 Jul 2009 04:54
Last Modified: 19 Sep 2010 05:24
URI: http://eprints.iisc.ac.in/id/eprint/18639

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