耦合形貌对Si4团簇电子输运影响的第一性原理计算

运用密度泛函理论与非平衡格林函数相结合的方法，对Si₄团簇与Au （100）-3×3两电极以顶位-顶位、顶位-空位、空位-空位三种形貌相连构成的Au-Si₄-Au纳米结点的拉伸过程进行第一性原理模拟，计算不同构型纳米结点在不同距离的电导和结合能.讨论耦合形貌、距离对结点电导的影响，结合能的计算表明三种不同耦合形貌结点存在稳定平衡结构，其平衡电导分别为0.71 G₀、0.96 G₀和2.44 G₀，且在-1.2 V~1.2 V的电压范围内，三种不同耦合形貌结点稳定结构表现出类似金属的导电特性，其I-V关系都近似为直线.计算结果表明Si₄团簇与电极的耦合形貌、两极距离对纳米结点电子输运有重要影响.

Influence of Contact Geometry on Electrical Transport Properties of Si4 Cluster: First Principles Study

Influence of contact geometry including coupling morphology and distances on electrical transport properties of Si₄ cluster coupled to two atomic Au(100)-3×3 electrodes is investigated from first principles with a combination of density functional theory and non-equilibrium Green's function method. Following situations of coupling morphology are considered:Si₄ cluster is sandwiched between two atomic Au electrodes at top to top, top to hollow, hollow to hollow position. We optimize geometry of junctions at different distances. We calculate cohesion energy and conductance of junctions as a function of distance d_z, and simulate Au-Si₄-Au junctions breaking process. We obtain equilibrium conductances of the most stable structures for different coupling morphology. They are 0.71 G₀, 0.96 G₀, 2.44 G₀, respectively. All junctions at stable structure have great conductance. In the range of voltage from -1.2 V to 1.2 V, I-V curve of junctions in the most stable structure shows linear characteristics. It shows that conductance is sensitive to coupling morphology and contact distance.