Ratchet dynamics of large polarons in asymmetric diatomic molecular chains

Abstract

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We study the dynamics of large polarons in diatomic molecular chains, at zero temperature, under the influence of an external, periodic in time, electric field with zero mean value. We show that in asymmetric chains, i.e., chains with two different atoms per unit cell, a harmonic unbiased field causes a drift of such polarons. Such a drift current, known as ratchet phenomenon, depends strongly on the parameters of the chain; in particular, on the extent of the anisotropy of the chain and on the size of the polaron. Moreover, the drift takes place only if the intensity and the period of the field exceed some critical values which also depend on the parameters of the chain. We show, that this directed current of polarons is a complicated phenomenon. It takes place in dissipative systems with a broken spatial symmetry, and is generated by the interplay between the PeierlsNabarro barrier and the impact of the external field on the charged polarons. The dependence of the amplitude of the polaron oscillations, the size of the drift per period of the external field and the average velocity are determined as a function of the intensity of the field and of its frequency.

On the non-thermal effects of electromagnetic fields on charge transport processes in ecosystems

“…Ratchet dynamics of solitons in nonlinear systems, described by nonlinear equations, such as sine-Gordon, was proven numerically (see, e.g., Zolotaryuk and Salerno [12], Gorbach et al [13]). Also it has been shown by Brizhik et al [14] that charged solitons can drift in molecular chains in the non-biased a.c. EMF. Appearance of such uni-directed motion is a critical phenomenon with respect to the intensity of the field and its frequency.…”

“…(8)- (9), γ is the friction coefficient, and q is the charge of a particle (q=e for a soliton, q=2e for a bisoliton, e is the elementary charge). In the simplest case the lattice potential is represented as a double-well periodic potential As it has been shown in Brizhik et al [14], such drift takes place only when the intensity of the field exceeds some critical value, which depends on the parameter values of the system, and in the fields whose frequency is not too high, namely, if it is less than the characteristic frequency of (bi)soliton (10) or (11), respectively. These conditions are necessary to allow (bi)soliton to overcome the potential barrier and the velocity (and frequency of oscillations) should be low enough so that the chain deformation could follow fast dynamics of electrons.…”

A generalised Davydov-Scott model for polarons in linear peptide chains

“…We adopt this Hamiltonian for our model, and following [12][13][14] we consider an additional external Hamiltonian,Ĥ ext , so that our Hamiltonian takes the form…”

“…It should therefore be possible that polaronic a e-mail: b.m.a.g.piette@durham.ac.uk transport of electrons may take place in proteins, too. Recently, Brizhik et al reported on the properties of static and dynamical polarons in simple molecular chains, and adverted to the applicability of their results to electron transport in biomolecules such as proteins [12][13][14]. Their studies were based on the Davydov-Scott model.…”

Donor-acceptor electron transport mediated by solitons

“…Moreover, for the chain itself, we have taken exactly the same parameters as in [57], i.e., C = 0.88 and G = 0.8, which correspond to the physical values of polypeptides and conducting polymers. For most of our simulations, we have used the value = 0.2.…”