中文摘要：

结合密度泛函理论和非平衡格林函数方法计算了溶液酸碱性对低聚苯亚乙炔基分子结电输运性质的影响，此低聚苯亚乙炔基分子中两个不同位置的H原子被氨基和羧基取代。通过质子化和去质子化模拟酸性溶液和碱性溶液对分子结构的影响。计算结果表明：中性环境下分子器件具有良好的导电性和微弱的整流效应；碱性溶液中羧基去质子化后，分子器件电流值增长近一倍，但整流效应变化不明显；酸性溶液中氨基质子化后，分子器件正向偏压导电性能略微降低，但整流方向发生明显反转，且与中性环境下的情况相比，整流比提高了近三倍。提出了一种利用化学手段控制分子结导电能力和整流性能的方法。

英文摘要：

Using nonequilibrium Green’s function method combined with density functional theory, we theoretically investigate the influences of alkaline and acid solutions on electronic transport properties in oligophenyleneethynylene molecular junctions with amino and carboxylic groups. The numerical results show that comparing with the case of neutral state, the conductance of the molecular junction is double improved and the rectifying direction is inverted when carboxylic group is deprotonated in the alkaline environment. On the other hand, the rectification ratio is enhanced trebly and the rectifying direction is inverted similarly when amino group is protonated in the acid environment. This theoretical work presents a chemically controllable method of manipulating conductance and rectification of molecular junctions.