外电场作用下寡聚苯分子导线的性质

Properties of Oligo-polyphenylene Molecular Wires under External Electric Field

利用Hartree—Fock方法在6-31G^＊水平上对聚苯分子进行了计算研究．分别从几何构型、分子轨道空间分布和分子轨道能级三个方面讨论了外电场对寡聚苯分子导线的影响，给出了分子导线的性质与外电场的关系．进一步，连接硫原子于聚苯分子的两端，并共价结合在金电极上．利用非平衡格林函数方法对其在0—2．0V偏压下电子输运特征进行了深入研究．

Theoretical investigations of conducting molecular wire of oligo-polyphenylene molecules under external electronic field were carded out using ab initio Haree-Fock method with 6-31G^＊ basis set. The electric field dependence of the molecular geometry, electronic structure, the spatial distribution, and the energy level of the frontier orbitals of the molecular wire was revealed. The torsion angle deviation was a function of square of electric field. When the external electric field increased, the torsion angles became smaller, the single bonds became shorter, and the molecular configuration tended to be more planar. All these features made the molecular wire more conjugated. The molecular electronic structure was sensitive to the electric field as well. With increasing electric field, the HOMO-LUMO gap decreased. Moreover, the spatial distribution of LUMO moved to the high potential end, whereas HOMO to the low potential end. Furthermore, the polyphenylene （PP） molecule with sulfur atoms bridged between two gold electrodes was studied by non-equilibrium Green＇s function formalism to further understand the electron transport of molecular wire under external electric field.