Finite-bias electronic transport of molecules in a water solution
Finite-bias electronic transport of molecules in a water solution
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DOI：
10.1103/physrevb.81.235407
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发表时间：
2010-06-04
影响因子：
3.7
通讯作者：
Sanvito, S.
中科院分区：
文献类型：
--
作者：
Rungger, I.;Chen, X.;Sanvito, S.
通过结合经验势分子动力学和第一原理电子传输计算，从理论上研究了水润湿条件对分子纳米结传输特性的影响。这些处于为自相互作用校正密度泛函理论实施的非平衡格林函数方法的水平。我们发现水有效地对分子结产生静电门控，其门控电位由时间平均水偶极场决定。对于极性苯二硫醇分子来说，这样的场很大，导致透射光谱相对于干结的透射光谱偏移约 0.6 eV。碳纳米管（CNT）的情况则截然不同。事实上，由于其疏水性，选通几乎可以忽略不计，因此湿 Au/CNT/Au 结的平均透射光谱基本上与干燥条件下的相同。这表明碳纳米管在水润湿的情况下也可以用作分子互连，例如，作为溶液或生物传感器中扫描隧道显微镜的尖端。
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.