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利用基于非平衡Green函数加密度泛函理论的第一原理方法,研究了以S(Se)为端基的三并苯环分子夹在两半无限长的Au电极之间构成双探针系统的输运特性,发现体系具有较好的整流效应,最大整流系数达到6;用H取代右端同一位置的一个S(Se),整流行为明显减弱.分析认为,这种整流是由于分子两端与电极的耦合不对称,使正负偏压下分子能级的移动和空间轨道分布不同所致.比较而言,S端基与电极的耦合导致的整流比Se强.
By using the first principle method based on the density functional theory of non-equilibrium Green’s function, we study that the double-probe system is composed of triacene ring molecules with S (Se) as the end group sandwiched between two halves of Au electrodes The results show that the system has a good rectification effect with a maximum rectification coefficient of 6, and H replaces a S (Se) at the same position at the right end, and the rectification behavior is obviously weakened.Analysis shows that this rectification is due to the fact that both ends of the molecule and the electrode Of the coupling asymmetry, so that the positive and negative bias molecular energy levels due to the movement and the distribution of space orbits due to the comparison, S terminal and the electrode coupling caused by the rectification ratio Se strong.