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DYNAMIQUE VIBRATIONNELLE MULTI-QUANTA DANS LES RÉSEAUX QUANTIQUES NON LINÉAIRES: Polarons et bi-polarons dans les bio-polymères et les nanostructures moléculaires

Abstract : In this theoretical work, we study the vibrational multi-quanta dynamics of nonlinear quantum lattices. Such lattices exhibit a periodic distribution of high-frequency vibrational modes whose dynamics originates in the interplay between the following phenomenons:
The dipole-dipole coupling leads to the delocalization of the vibrations and to the formation of vibrational excitons called vibrons.
The intramolecular anharmonicity favors an attractive interaction between vibrons responsible for the occurrence of bound states. These states are characterized by a localization of the vibron interdistance and can be viewed as the quantum counterpart of nonlinear classical object like solitons.
The vibron-phonon interaction modifies the dynamics through the dressing effect which yields the formation of a polaron, i.e. a vibron dressed by a lattice distortion. This effect induces an increase of the polaron reduced mass and acts as a second nonlinear source.

This formalism, applied to alpha-helices and to molecular nanostructures, gives the following results:
At biological temperature, an alpha-helix is well described by a 1D model and supports two kinds of bound states which have been observed experimentally. By contrast, at low temperature, the 3D nature of the polaronic states is enhanced.
In a finite size nanowire, the singularity of the dressing effect yields the formation of localized states.
The local and nonlocal nonlinearities allow for a coherent energy transfer mediated by specific bound states.
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https://tel.archives-ouvertes.fr/tel-00128559
Contributor : Cyril Falvo <>
Submitted on : Thursday, February 1, 2007 - 5:04:21 PM
Last modification on : Tuesday, December 8, 2020 - 2:40:05 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 11:00:29 PM

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  • HAL Id : tel-00128559, version 1

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Cyril Falvo. DYNAMIQUE VIBRATIONNELLE MULTI-QUANTA DANS LES RÉSEAUX QUANTIQUES NON LINÉAIRES: Polarons et bi-polarons dans les bio-polymères et les nanostructures moléculaires. Physique Atomique [physics.atom-ph]. Université de Franche-Comté, 2006. Français. ⟨tel-00128559⟩

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