First-principles transversal DNA conductance deconstructed
Xiaoguang Zhang 1*, Predrag S Krstic 1, Radomir Ziki 1, Jack Wells 1 and Miguel Fuentes-Cabrera 1
1 Oak Ridge National Laboratory
* To whom correspondence should be addressed. E-mail: xgz{at}ornl.gov.
Submitted on March 21, 2006
Revised on April 26, 2006
Accepted on 28 April 2006
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Abstract |
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First-principles calculation of the transverse conductance across DNA fragments placed between gold nanoelectrodes, reveals that such conductance describes electron tunneling that depends critically on geometrical rather than electronic-structure properties. By factoring the first-principles result into two simple and approximately independent tunneling factors, we show that the conductances of the A, C, G, and T fragments differ only because of their sizes: the larger is the DNA base, the smaller its distance to the electrodes, and the larger is its conductance. Because the geometrical factors are difficult to control in an experiment, the DC-current measurements across DNA with gold contact electrodes may not be a convenient approach to DNA sequencing.
Key Words:
HOMO-LUMO gap, conductance, nucleotide, tunneling
