COULOMB INTERACTIONS AND SOLITON MODEL DYNAMICS IN QUASI - ONE-DIMENSIONAL SYSTEMS (POLYACETYLENE, PHOTO EXCITATION, EXCITON).
Item
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Title
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COULOMB INTERACTIONS AND SOLITON MODEL DYNAMICS IN QUASI - ONE-DIMENSIONAL SYSTEMS (POLYACETYLENE, PHOTO EXCITATION, EXCITON).
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Identifier
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AAI8708326
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identifier
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8708326
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Creator
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WANG, CHUI-LIN.
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Contributor
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Frank Martino | Melvin Lax
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter
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Abstract
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The Su-Schrieffer-Heeger (SSH) soliton model and its continuum version, the Takayama-Lin-liu-Maki (TLM) model, are presented and their solutions for both the dimerized ground states and the soliton excited states are discussed. The dynamical effects of the electron-electron Coulomb interaction in degenerate systems are studied by using the SSH-extended Hubbard model. We find from numerical simulation that two possible states may be photogenerated depending on the energy gained by the system. If the system energy is higher than a critical value, soliton-antisoliton pairs are photogenerated and are free to separate, leaving behind a central breather mode. If the system energy is lower than the critical value, the soliton-antisoliton pairs will bind and form a different central oscillation: an exciton-breather. The critical energy is slightly above the soliton pair creation energy. We interpret this exciton-breather to be the origin of the observed infrared activity "pinning" mode at 500 cm('-1) in trans-polyacetylene, and the cause of the disappearance of the photoconductivity at low temperature.;Nondegenerate conjugated polymers are also studied by means of a modified SSH-type model Hamiltonian. We present numerical solutions representing a bipolaron-breather mode, which oscillates between two stages (a kink-antikink pair and a bound polaron pair). We show that the creation of such a bipolaron can be energetically favorable in the case of either doping or photoexcitation. Our results compare well with the experimental photoluminescence spectrum of cis-(CH)(,x).
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Physics
