dorsal/arxiv
View SchemaTwo-vibron bound states in alpha-helix proteins : the interplay between the intramolecular anharmonicity and the strong vibron-phonon coupling
| Authors | Vincent Pouthier |
|---|---|
| Categories | |
| ArXiv ID | physics/0306044 |
| URL | https://arxiv.org/abs/physics/0306044 |
| DOI | 10.1103/PhysRevE.68.021909 |
Abstract
The influence of the intramolecular anharmonicity and the strong vibron-phonon coupling on the two-vibron dynamics in an $\alpha$-helix protein is studied within a modified Davydov model. The intramolecular anharmonicity of each amide-I vibration is considered and the vibron dynamics is described according to the small polaron approach. A unitary transformation is performed to remove the intramolecular anharmonicity and a modified Lang-Firsov transformation is applied to renormalize the vibron-phonon interaction. Then, a mean field procedure is realized to obtain the dressed anharmonic vibron Hamiltonian. It is shown that the anharmonicity modifies the vibron-phonon interaction which results in an enhancement of the dressing effect. In addition, both the anharmonicity and the dressing favor the occurrence of two different bound states which the properties strongly depend on the interplay between the anharmonicity and the dressing. Such a dependence was summarized in a phase diagram which characterizes the number and the nature of the bound states as a function of the relevant parameters of the problem. For a significant anharmonicity, the low frequency bound states describe two vibrons trapped onto the same amide-I vibration whereas the high frequency bound states refer to the trapping of the two vibrons onto nearest neighbor amide-I vibrations.
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"abstract": "The influence of the intramolecular anharmonicity and the strong\nvibron-phonon coupling on the two-vibron dynamics in an $\\alpha$-helix protein\nis studied within a modified Davydov model. The intramolecular anharmonicity of\neach amide-I vibration is considered and the vibron dynamics is described\naccording to the small polaron approach. A unitary transformation is performed\nto remove the intramolecular anharmonicity and a modified Lang-Firsov\ntransformation is applied to renormalize the vibron-phonon interaction. Then, a\nmean field procedure is realized to obtain the dressed anharmonic vibron\nHamiltonian. It is shown that the anharmonicity modifies the vibron-phonon\ninteraction which results in an enhancement of the dressing effect. In\naddition, both the anharmonicity and the dressing favor the occurrence of two\ndifferent bound states which the properties strongly depend on the interplay\nbetween the anharmonicity and the dressing. Such a dependence was summarized in\na phase diagram which characterizes the number and the nature of the bound\nstates as a function of the relevant parameters of the problem. For a\nsignificant anharmonicity, the low frequency bound states describe two vibrons\ntrapped onto the same amide-I vibration whereas the high frequency bound states\nrefer to the trapping of the two vibrons onto nearest neighbor amide-I\nvibrations.",
"arxiv_id": "physics/0306044",
"authors": [
"Vincent Pouthier"
],
"categories": [
"physics.bio-ph"
],
"doi": "10.1103/PhysRevE.68.021909",
"title": "Two-vibron bound states in alpha-helix proteins : the interplay between the intramolecular anharmonicity and the strong vibron-phonon coupling",
"url": "https://arxiv.org/abs/physics/0306044"
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