Vibron transport in macromolecular chains

We study the hopping mechanism of the vibron excitation transport in the simple 1D model of biological macromolecular chains. We supposed that the vibron interaction with thermal oscillations of the macromolecular structural elements will result in vibron self -trapping, and the formation of the partial dressed vibron state. With use of the modified Holstein polaron model, we calculate vibron diffusivity in dependence of the basic system parameters and temperature. We obtain that the vibron diffusivity smoothly decreases in non adiabatic limit when the strength of the vibron-phonon coupling grows. However this dependence becomes by discontinuous one in case of growth of the adiabaticity of the system. The value of the critical point depends of the system temperature, and at room temperatures it belongs to the low or intermediate coupling regime. We discuss an application of these results to study of vibron transport to 3D bundles of such macromolecules chains considering it as polymer nanorods and to 2D polymer films organized from such macromolecules.Comment: 4 pages, 6 figures, contribution to the Proceedings of the Conference "Physical mesomechanics of multi-level systems`2014", September 3-5 2014, Tomsk, Russi

Influence of the electron-phonon iinteraction on phonon heat conduction in a molecular nanowire

A model for phonon heat conduction in a molecular nanowire is developed. The calculation takes into account modification of the acoustic phonon dispersion relation due to the electron-phonon interaction. The results obtained are compared with models based upon a simpler, Callaway formula

On the vibron dressing in the α\alpha--helicoidal macromolecular chains

We present a study of the physical properties of the vibrational excitation in $\alpha$--helicoidal macromolecular chains, caused by the interaction with acoustical and optical phonon modes. The influence of the temperature and the basic system parameters on the vibron dressing has been analyzed by employing the simple mean--field approach based on the variational extension of the Lang--Firsov unitary transformation. Applied approach predicts a region in system parameter space where one takes place an abrupt transition from partially dressed (light and mobile) to fully dressed (immobile) vibron states. We found that the boundary of this region depends on system temperature and type of bond among structural elements in the macromolecular chain.Comment: 22 pages, 12 figures, title changed, the interaction with optical phonon modes jointly with acoustical ones added, consideration significantly enlarged, references added, the paper develops the results of arxiv:1210.3918, accepted for publication in Chinese Physics

Phonon hardening due to the small-polaron effect

The influence of the small-polaron effect on the vibrational properties of the strongly coupled electron-phonon system is investigated. It was found that polaron-phonon interaction may cause a noticeable renormalization of the phonon spectra. These changes may be observed by the measurements of the speed of sound for which a very specific dependence on temperature, values of coupling constant and adiabatic parameter is expected. We also found that the rise of the small-polaron effective mass as a function of the coupling constant should be considerably moderated than that anticipated without taking into account the modification of the vibrational spectra. (C) 2004 Elsevier B.V. All rights reserved

Small-polaron resistivity of the narrow band molecular chain: The influence of phonon hardening

We study the effect of the small-polaron induced changes of phonon spectra on charge transfer in molecular solids. Noticeable discrepancy with the predictions of the traditional small-polaron theories is observed: accounting of phonon hardening yields significantly lower estimates for small-polaron resistivity than that obtained on the basis of conventional approaches. This especially concerns the low temperature limit in which transport processes are dominated by the band like motion of charge carriers. This difference gradually disappears with the increasing of coupling constant and temperature. (c) 2005 Elsevier B.V. All rights reserved