单硫醇分子结的几何结构和电输运性质:压力效应与末端基团效应

Geometric structure and electronic transport property of single alkanemonothiol molecule junction: external force effect and terminal group effect

利用杂化密度泛函理论,研究了以甲基、醇基、羧基为末端基团的烷烃硫醇分子与金电极形成分子结的过程,得到了分子结的几何结构与外加压力的关系.并在此基础上,利用弹性散射格林函数方法研究了烷烃硫醇分子的电输运性质.研究结果表明,对于C11S分子来说,当两电极距离大于2.1nm时,该分子结断裂;对于C11SOH和C10SCOOH来说,相应的分子结断裂的电极距离基本相同(2.15nm).在相同的外加压力(4.0nN)下,C11S分子的导电能力最强,其次是C11SOH分子,而C10SCOOH分子的导电能力最差.随着压力的增加,三种分子结的电导呈现出单调地增加,且在相同的外加压力下,三种分子导电能力的强弱没有改变.理论计算结果与实验结果定性地符合.

The hybrid density functional theory is used to study formation of the junction of alkanemonothiol molecules with different terminal groups. The relationship between geometric structures of the molecular junction and the external force is obtained. On the basis of the relationship, the electronic transport properties of the molecular junctions under different external forces are investigated using the elastic-scattering molecular junction is broken when the distance of the two Green＇ s function method. The results show that the CH S electrodes is larger than 2.1 nm. While for CH SOH and C10SCOOH molecular junctions, their critical distances are similarly 2. 15 nm. Taking the same external force, we find that the CH S molecule has the largest conducting ability, and the C10SCOOH molecule has the smallest conducting ability. Furthermore, the conductance of the three molecular junctions is monotonically enhanced with the increase of the external force. The numerical results are consistent with the experimental findings qualitatively.