分子链长对烷烃硫醇分子电输运性质的影响

The effect of molecular length on electronic transport properties of alkanemonothiol molecules

在杂化密度泛函理论的基础上,利用弹性散射格林函数方法研究了烷烃硫醇系列分子的电输运性质,并同实验结果进行了比较.研究结果表明,在低的外加偏压下,烷烃硫醇分子电流值随着分子链长度的增加而指数减小,其衰减常数约为l. 41/CH_2,且衰减常数基本上与外加偏压值的大小无关.分子末端原子与探针的距离具有较大地自由度,不同的接触距离导致了分子的电流值有较大地差别.

The elastic- scattering Green＇s function method is applied to study the electronic transport properties of alkanemonothiol molecules at the hybrid density functional theory level. The numerical results are compared with experimental measurements. The results show that, in the lower voltage regime, the molecular currents decreased exponentially with the molecular length, and the corresponding decay constant is about 1.41/CH2. Furthermore, the decay constant is demonstrated to be almost independent of the external voltage. The distance between the terminal atom and the probe of conduction atomic force microscopy is quite flexible, and the electronic transport properties of molecules are sensitive to the distance.