Charge Transfer in DNA: The Role of Large Polarons

Polaronic mechanism of charge transfer in DNA is considered on the basis of one-dimensional Su-Schrieffer-Heeger (SSH) model Hamiltonian. It is shown that usually used values of SSH model Hamiltonian parameters, especially transfer integral and electron-phonon coupling constant which are obtained in the framework of ab initio calculations, do not give reliable resolution of the problem of (large) polaron applicability for charge migration in DNA. Because of that, theoretical method is proposed which enables us to estimate explicitly electron-phonon coupling constant on the basis of transfer integral. The value of polaron width obtained for such determined parameters leads to the conclusion that coherent motion of large polaron represents dominant mechanism of charge transfer in DNA.9th International Frohlichs Symposium on Electrodynamic Activity of Living Cells - Including Microtubule Coherent Modes and Cancer Cell Physics, Jul 01-03, 2011, Prague, Czech Republi

Charge transport in the alpha-helix proteins

In this paper we investigate charge transport in the alpha-helix proteins. It is considered that charge carriers are partially dressed small polarons, that are formed by electron self-trapping in the weak coupling limit. Polaron properties are considered by applying mean-field theory based upon the modified Lang-Firsov transformation and the Bogolyubov theorem. The transport properties have been calculated on the basis of the Holstein MC model. The obtained results are compared with the results of previous models.International Conference on Theoretical Physics Dubna-Nano 2010, Jul 05-10, 2010, Dubna, Russi

Nonlinear dynamics of microtubules and series expansion unknown function method

Microtubules (MTs) are the most important part of cytoskeleton. In this paper we deal with two basic nonlinear differential equations coming from the two known models describing nonlinear dynamics of MTs. These equations are solved using the series expansion unknown function method (SEUFM). Trying to recognize the most general mathematical procedure for solving these equations the solutions are compared with those obtained earlier using the tangent hyperbolic function method (THFM) and the simplest equation method (SEM). In all these three approaches we express the solutions of these equations as series expansions. In the cases of THFM and SEM the functions existing in the series are known while SEUFM assumes unknown function

Damping and modification of the multiquanta Davydov-like solitons in molecular chains

Relaxation of the multivibron soliton in molecular chain on lattice vibrations is investigated within the simple microscopic model. It was shown that its dynamics is governed by the nonlinear Schrodinger equation containing damping term. Its appearance is the consequence of the emission and absorption of real phonons arising when soliton velocity approaches the phase speed of sound. Explicit time dependence of the soliton parameters results as a consequence of these perturbations. In particular, soliton amplitude decreases while its width increases. (C) 1999 Elsevier Science S.A. All rights reserved.Symposium on Electromagnetic Fields in Biological Systems, Sep 13-16, 1998, Prague, Czech Republi

Finite-temperature large acoustic polaron dynamics in quasi-one-dimensional molecular crystals

We report the results of theoretical examinations of large polaron motion in one-dimensional (1D) molecular crystals under the influence of thermal fluctuations of the host lattice and constant electric field. Such a situation may arise in biological macromolecules such as an alpha helix where charge (electron) transfer may be achieved by a polaron (soliton) mechanism. In that case, the electric field represents the effective endogenous electric field which is always present in realistic conditions. We derive and solve the Fokker-Planck equation for the distribution function of the solitons center-of-mass position. It is shown that the soliton effectively exhibits a random walk. Moreover, in order to examine statistical properties of the soliton wave function, we calculate the mean value of the soliton probability density: LT \beta(x,t)\(2) GT and we find that, for sufficiently large times, thermal fluctuations destruct the soliton, which transforms into the Gaussian packet. These results were used in order to estimate the relevance of the soliton model of charge transfer in polypeptide chains

Radiative decay of the one-dimensional large acoustic polaron

Finite temperature dynamics and stability of the adiabatic large acoustic polaron in one-dimensional systems have been examined by means of the perturbation method based upon the inverse scattering transform. Polaron life-time was estimated in dependence of temperature and electron (exciton)-phonon coupling constant. (C) 2002 Elsevier Science B.V. All rights reserved

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

On the possible role of small polarons in the charge and energy transport in the alpha-helix proteins

We study the possibility of the small-polaron creation in alpha-helix proteins, accounting for the self-trapping of the intramolecular vibration energy quanta. The small-polaron concept of energy transfer in polypeptides has been revisited on the basis of these results. It was found that traditional small-polaron theories cannot be directly applied to the vibrational quanta transfer in these substances. In particular, true eigenstates of system should correspond to a partial dressed polarons rather than to the fully dressed small polaron states.Bogolyubov Conference on Modern Problems of Mathematical and Theoretical Physics, Sep 15-18, 2009, Kyiv, Ukrain