双笼氟化富勒烯分子C_(20)F_(18)(CO)_2C_(20)F_(18)电子输运性能的第一性原理研究

First-principles investigation of electronic transport properties of molecular device based on double-cage fluorinated fullerene C_(20)F_(18)(CO)_2C_(20)F_(18)

以双笼氟化富勒烯C_(20)F_(18)(CO)_2C_(20)F_(18)为中心分子,与Ag(100)纳米线电极连接构筑分子电子器件,通过第一性原理和非平衡格林函数相结合的方法,对器件的电子输运特性进行了研究.结果显示,在外加偏压的作用下,中心分子的前线轨道逐渐定域在分子的左侧,电子透射通道被阻塞,所对应的共振隧穿峰被压制,器件的电流-电压特性曲线在0.3~0.8V区间内表现出明显的负微分电阻(NDR)现象.

The transport properties of molecular device based on C_（20）F_（18）（CO）_2C_（20）F_（18） has been studied using non-equilibrium Green＇s function method combined with density functional theory.The calculation result shows that the current-voltage characteristic of the device displays remarkable negative differential resistance（NDR）behaviors in the range of 0.3 to 0.8 V.The investigation on the transmission spectrum and transmission eigenstate under different bias showed that the LUMO of central molecule gradually localized on the left part of it under the effect of bias,leading to the transmission channels has been blocked,and the corresponding resonant tunneling peak has been suppressed,is the major reason of the NDR.