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Distance-dependent coherent charge transport in DNA: crossover from tunneling to free propagation

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DOI: 10.4236/jbpc.2010.12010    5,451 Downloads   10,358 Views Citations

ABSTRACT

Using a tight-binding model, we investigate the influence of intra- and interstand coupling parameters on the charge transport properties in a G-(T)j-GGG DNA sequence and its (G:C)-(T:A)j-(G:C)3 duplex attached to four electrodes. Dependences of the transmission function and of the corresponding conductance of the system on the number of bridging sites were obtained. Simulation results of a recently proposed two-strand superexchange (tunneling) model were reproduced and extended. It is demonstrated that the crossover from strong to weak distance-dependent charge transport is elucidated by a transition from under-barrier tunneling mechanism to free over-barrier propagation in the coherent regime, controlled by temperature and coupling parameters. The role of DNA- electrode coupling has been also considered. It was found that an asymmetry in the DNA-electrode coupling has a drastic effect on the con-ductance leading to an increase in delocaliza-tion of the electronic states in the DNA duplex.

Cite this paper

Grib, N. , Ryndyk, D. , Gutiérrez, R. and Cuniberti, G. (2010) Distance-dependent coherent charge transport in DNA: crossover from tunneling to free propagation. Journal of Biophysical Chemistry, 1, 77-85. doi: 10.4236/jbpc.2010.12010.

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