Au-Si_(60)-Au分子结电子输运性质的理论计算  

Theoretical calculation of electron transport properties of the Au-Si_(60)-Au molecular junctions

作　　者：柳福提[1,2,3] 程艳[2] 陈向荣[2] 程晓洪[1] 曾志强[1,3] 

机构地区：[1]宜宾学院物理与电子工程学院,宜宾644007 [2]四川大学物理科学与技术学院,成都610064 [3]宜宾学院计算物理四川省高校重点实验室,宜宾644007

出　　处：《物理学报》2014年第17期271-276,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11174214;11204192);四川省教育厅科研基金(批准号:13ZB0207);宜宾学院重点科研基金(批准号:2013YY05)资助的课题~~

摘　　要：运用密度泛函理论对Si60团簇的结构进行几何优化,得到基态结构是一个直径为1.131 nm,平均键长为0.239 nm,分子最低未占据轨道与最高占据轨道能量差即能隙值为0.72 eV,具有C1点群的空心笼状结构.然后把它与两半无限的Au(100)-4×4电极相连构成Au-Si60-Au三明治结构分子结点,运用密度泛函理论结合非平衡格林函数的方法对其电子输运性质进行了第一性原理计算.当两电极的距离为1.74 nm时,分子结点的平衡电导为1.93G0(G0=2e2/h),然后在-2.0—2.0 V的电压范围内,计算了不同电压下的电导与电流,得到其I-V曲线成近线性关系,从分子前线轨道与透射谱分析了Si60分子的电子输运特性,讨论了电荷转移量与电导之间的关系.The ground structure of Si60 clusters, which was obtained by optimization when using the density functional theory method, is a fullerene structure with C1 point group, a diameter 1.131 nm, the average bond length 0.239 nm, and the difference between the energies of the lowest unoccupied molecular orbital and the highest occupied molecular orbital is 0.72 eV. A Si60 cluster with optimized structure is sandwiched between two semi-infinite Au（100）-4 × 4 electrodes, and the Au-Si60-Au molecular junctions is constructed, whose electron transport properties is investigated with a combination of density functional theory and non-equilibrium Green＇s function method. When the distance between the two electrodes is 1.74 nm, the equilibrium conductance of the junctions is 1.93 Go （Go = 2e2/h）. In the range of voltage from -2.0--2.0 V, we have calculated the current and conductance under different voltages, and find that the I-V curve of the junctions show linear characteristics. We also analyze the properties of transport from transmission and frontier molecular orbitals, and discuss the relationship of transfer charge with conductance.

关 键 词：电子输运 密度泛函理论 非平衡格林函数 Au—Si60-Au分子结 

分 类 号：O561[理学—原子与分子物理]