Dissipative effects in the electronic transport through DNA molecular wires

Abstract

We investigate the influence of a dissipative environment which effectively comprises the effects of counterions and hydration shells, on the transport properties of short DNA wires. Their electronic structure is captured by a tight-binding model which is embedded in a bath consisting of a collection of harmonic oscillators. Without coupling to the bath a temperature independent gap opens in the electronic spectrum. Upon allowing for electron-bath interaction the gap becomes temperature dependent. It increases with temperature in the weak-coupling limit to the bath degrees of freedom. In the strong-coupling regime a bath-induced pseudo-gap is formed. As a result, a crossover from tunneling to activated behavior in the low-voltage region of the I-V characteristics is observed with increasing temperature. The temperature dependence of the transmission near the Fermi energy, t(EF), manifests an Arrhenius-like behavior in agreement with recent transport experiments. Moreover, t(EF) shows a weak exponential dependence on the wire length, typical of strong incoherent transport. Disorder effects smear the electronic bands, but do not appreciably affect the pseudo-gap formation.

Inelastic effects in molecular transport junctions: The probe technique at high bias

“…In Donor-Acceptor junctions, phonon emission and absorption processes facilitate charge transfer between two molecular electronic sites (or orbitals) [12][13][14][15][19][20][21][22] . Tightbinding models with several electronic sites and multiple vibrational modes have been employed to describe charge transfer in extended molecules, linear organic molecules 18 , and DNA 23 .…”

Electrical conductance in duplex DNA: Helical effects and low-frequency vibrational coupling

“…The role of thermal fluctuations on the charge transfer efficiency has been discussed in a number of recent papers where the structural fluctuations of the DNA double helix are described by sampling the initial angular velocities and twist angles from a Boltzmann distribution at a given temperature. [18][19][20][21][22][23][24] In this work we will focus on coherent transport due to the coupling between low-frequency vibration modes and charge motion through duplex DNA, and we will explicitly take into account its characteristic helical geometry.…”

DNA-based thermoelectric devices: A theoretical prospective

“…52 A possible way to account for dephasing effects within the Landauer approach consists in coupling a dephasing term to every site of the DNA backbone. 53,54 The main effect of such a coupling is then to modify the ␥ value. In a previous work we explicitly considered the possible influence of a relatively wide fluctuation of such a parameter ͑⌬␥ = ±1 eV͒ on the main features of the thermopower curve of single-stranded DNA chains, concluding that the resonance peak in the thermopower curve is quite robust under the influence of local environmental effects.…”