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|Type:||Artigo de periódico|
|Title:||BAND TO CORRELATED CROSSOVER IN ALTERNATING HUBBARD AND PARISER-PARR-POPLE CHAINS - NATURE OF THE LOWEST SINGLET EXCITATION OF CONJUGATED POLYMERS|
|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.|
|Editor:||American Physical Soc|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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