中文摘要：

用从头算理论和弹性散射格利用林函数的方法,计算了电场作用下的4,4’-二吡啶杂环分子体系的电子结构及其电导和电流.计算结果表明,电场作用使得体系在分子和电极间存在电荷转移和重新分布的过程,使分子与电极接触面附近出现电子积聚区和电子耗散区,从而产生附加电偶极子,对分子的电导和电流产生抑制的影响.此外,在分子轨道能级和分子与电极的耦合系数上,电场的影响也比较明显,从而导致了分子的伏-安特性在考虑电场作用前后有较大的差异.考虑电场作用后的伏-安非线性特征与实验结果符合较好.

英文摘要：

By using ab initio theory and elastic scattering Green’s function method,the electronic structure of 4,4’-bipyridine molecule are investigated,so do the conductance and current.The numerical results show that the charge of system is transferred and redistributed by electric field’s action.The electrons gathering area and its dissipation area are formed near the interface between molecule and electrodes.So,the additional electric dipoles are formed,which will restrain the conductance and current of molecule.Moreover,the molecular orbit energy and the coupling coefficients between molecule and electrodes influenced obviously by electric field also,which will cause the difference of molecular voltage current characteristic fore and after considering electric field.The voltage current characteristic with consideration of electric field coincides better with the experimental results.