Band to correlated crossover in alternating Hubbard and Pariser-Parr-Pople chains: Nature of the lowest singlet excitation of conjugated polymers

Soos, ZG and Ramasesha, S and Galvão, DS (1993) Band to correlated crossover in alternating Hubbard and Pariser-Parr-Pople chains: Nature of the lowest singlet excitation of conjugated polymers. In: Physical Review Letters, 71 (10). pp. 1609-1612.

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Abstract

The evolution with increasing Coulomb correlations of a semiconductor to a magnetic insulator is related to an excited-state crossover in pi-electron models for conjugated polymers. We associate strong fluorescence with a lowest singlet excitation S1 that is dipole allowed, on the band side, while S1 becomes two-photon allowed on the correlated side. S1/S2 crossovers in Hubbard, Pariser-Parr-Pople, or other chains with electron-hole symmetry and alternating transfer integral t(1 +/- delta) are based on exact results at delta=0 and 1, on molecular exciton theory at large delta, and on oligomer calculations up to twelve sites.

Item Type:	Journal Article
Publication:	Physical Review Letters
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	02 Feb 2011 09:30
Last Modified:	02 Feb 2011 09:30
URI:	http://eprints.iisc.ac.in/id/eprint/35341

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