Symmetrized DMRG studies of low-energy electronic states of poly-paraphenylene (PPP) and poly-para-phenylenevinylene (PPV) systems

S. Ramasesha; Kunj S. Tandon; Y. Anusooya; Swapan K. Pati

doi:10.1117/12.295531

1 December 1997 Symmetrized DMRG studies of low-energy electronic states of poly-para-phenylene (PPP) and poly-para-phenylenevinylene (PPV) systems

S. Ramasesha, Kunj S. Tandon, Y. Anusooya, Swapan K. Pati

Author Affiliations +

Proceedings Volume 3145, Optical Probes of Conjugated Polymers; (1997) https://doi.org/10.1117/12.295531
Event: Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United States

Abstract

Symmetrized DMRG calculations on long oligomers of poly- para-phenylene (PPP) and poly-para-phenylene vinylene (PPV) systems within a `U-V' model have been carried out to obtain the one-photon, two-photon and singlet-triplet gaps in these systems. The extrapolated gaps (in eV) are 2.89, 3.76 and 2.72 in PPP and 3.01, 3.61 and 2.23 in PPV for the one- photon, two-photon and spin gaps respectively. By studying doped systems, we have obtained the exciton binding energies. The larger exciton binding energies, compared to strongly dimerized linear chains emphasizes the role of topology in these polymers. Bond orders, charge and spin correlations in the low-lying states bring out the similarities between the lowest one-photon, the lowest triplet and the lowest bipolaronic states in these systems. The two-photon state bond orders show evidence for strong localization of this excitation in both PPP and PPV systems.

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S. Ramasesha, Kunj S. Tandon, Y. Anusooya, and Swapan K. Pati "Symmetrized DMRG studies of low-energy electronic states of poly-para-phenylene (PPP) and poly-para-phenylenevinylene (PPV) systems", Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997); https://doi.org/10.1117/12.295531

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