中文摘要：

采用第一性原理的密度泛函理论和非平衡格林函数方法，将C20分子分别与不同的电极材料连接构建了电极-C20-电极三明治结构，研究了分子器件中不同的电极材料对分子器件电荷输运性质的影响．结果发现。当使用非对称的电极材料时，分子与左右电极的耦合程度不同，因此分子器件表现出整流行为，而使用对称性电极时并没有发现整流现象．这一现象的产生是由于正负偏压下的透射率的变化以及偏压窗内分子轨道空间分布的变化所致．我们的研究为分子整流器的产生提供了重要的理论指导．

英文摘要：

By using first -principles method, which combines density functional theory with non -equilibrium Greeng function, molecular device are constructed based on C20 connected into both electrodes with different metal materials. We investigate the effect of different electrode materials on the electronic transport properties of molecular devices. The results show that, the degrees of coupling between the molecule and electrodes are different when the devices are constructed with asymmetrical electrode materials; thus the current rectification is created. On the contrary, the rectification phenomenon disappears when the devices are constructed with symmetrical electrode materials. This rectification is fully rationalized by the variation of calculated transmis- sion spectra and the spatial distribution of the molecular orbitals within the bias windows. This will provide an important theoretical support for the fabrication of molecular rectifier.