Finite-bias electronic transport of molecules in a water solution
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Citation:I. Rungger, X. Chen, U. Schwingenschlogl, and S. Sanvito, Finite-bias electronic transport of molecules in a water solution, Physical Review B, 81, 2010, 235407
The effects of water wetting conditions on the transport properties of molecular nanojunctions are investigated theoretically by using a combination of empirical-potential molecular-dynamics and first-principles electronic-transport calculations. These are at the level of the nonequilibrium Green?s-function method implemented for self-interaction corrected density-functional theory. We find that water effectively produces electrostatic gating to the molecular junction with a gating potential determined by the time-averaged water dipole field. Such a field is large for the polar benzene-dithiol molecule, resulting in a transmission spectrum shifted by about 0.6 eV with respect to that of the dry junction. The situation is drastically different for carbon nanotubes CNTs . In fact, because of their hydrophobic nature the gating is almost negligible so that the average transmission spectrum of wet Au/CNT/Au junctions is essentially the same as that in dry conditions. This suggests that CNTs can be used as molecular interconnects also in water-wet situations, for instance, as tips for scanning tunnel microscopy in solution or in biological sensors.
Science Foundation Ireland
European Union (EU)
Publisher:American Physical Society
Series/Report no:Physical Review B;