 |
 |
*A Postdoctoral Research Associate appointment is available in the « Complexes Structures Dynamics » group of the UTINAM Institute in BESANCON (France). The details of the position are summarized below :* *Title : Energy transfer in nonlinear quantum lattices : application to the vibrational energy flow in alpha-helices* *Location: *UTINAM Institute UMR-CNRS 6213 Université de Franche-Comté 25030 Besançon, cedex FRANCE *Application deadline :** September the first, 2009* *Length: *9 months, starting as soon as possible considering the time needed by the person retained to get all the administrative papers necessary to work in France. *Financial conditions: * The credits obtained allow us to warrant a gross salary of 1839 EUR per month, which in reality means 1508 EUR per month transferred on the bank account. *Requested profile:* To develop these researches, we are looking for a candidate who has a strong background in either quantum non-linear dynamics, non equilibrium statistical mechanics, transport properties, dissipation, energy localization in molecular system or numerical analysis (i.e. ab initio calculations) applied to condensed or soft matter. In any case, *the person retained must have completed his/her PHD since less than 2 years* and NOT be of French nationality! Therefore, the applicants should enclose in their application, considerations allowing assessing the time they would need to get the authorization to work in France. *Contact :* The applicants should send a detailed CV and a publications list to Dr. POUTHIER Vincent at : [log in to unmask] <mailto:[log in to unmask]> *Summary of the project:* Since the seminal work of Davydov on bioenergy transport in proteins, both theoretical and experimental evidences suggest that vibrational energy flow in alpha-helices may result from a polaron mechanism. The energy is mediated by the amide-I vibration which delocalizes along the peptide leading to the formation of an exciton called vibron. The vibron strongly interacts with the phonons describing the collective dynamics of the H-bond network. Therefore, its creation induces a lattice distortion and the vibron dressed by this distortion forms the so-called small polaron. In that context, the project concerns the study of the transport properties of polaron or bi-polaron in a lattice of H bonded peptide units by taking into account on the very short lifetime of the amide-I vibration. Indeed, most of the previous works were based on Hamiltonians that conserve the polaron population. However, in proteins, the amide-I energy relaxation is rather fast and recent experiments have clearly shown that the polaron lifetime is typically of about T1=1.5 ps. The relaxation originates from intramolecular energy redistribution due to the anharmonic coupling between each amide-I mode and a set of intramolecular normal modes whose displacements are strongly localized on the C=O groups. Therefore, the Complex Structure Dynamics group of the UTINAM Institute is looking for a candidate able to develop one of the two following topics : - Developing analytical models/calculations to study the transport properties in a finite size helix within a time convolutionless approach to account on the strong non markovian dynamics that arises from the discrete nature of the phonon energy spectrum. *Application to other systems could be considered : quantum diffusion of narrow band exciton in lattice (anharmonic Holstein model, Anderson model with correlated disorder, Hubbard model ...)* - Performing ab initio calculations to characterize the detailed relaxation pathways responsible for the energy relaxation of the amide-I mode in a model helix. These calculations will give rise to a theoretical model to represent the bath of intramolecular normal modes responsible for energy relaxation. ** -- Dr. POUTHIER Vincent Chargé de Recherche CNRS Institut UTINAM UMR CNRS 6213 25030 BESANCON cedex tel. 33 3 81 66 64 77 To join or leave the molecular-dynamics-news email list, go to: http://www.jiscmail.ac.uk/lists/molecular-dynamics-news.html