二苯乙炔分子导线的电子输运性质

Electron Transport Properties of Diphenylacetylene Molecular Wire

利用第一性原理非平衡态格林函数方法研究了不同构象下二苯乙炔分子导线的电子输运性质.从分子轨道空间分布和透射谱等方面讨论了外加偏压下分子构象对电子传递特性的影响及内在机理.结果表明,随着分子扭转角的增加,分子的LUMO-HOMO能隙增加,透射峰显著降低;外加偏压下,分子的HOMO分布向低电势端移动,LUMO向高电势端移动.电流-电压计算表明,平面构象分子的导电性最好;随着扭转角的增加,分子的导电性变差;垂直构象分子的导电性最差.最后给出了分子导线电子传递性质与分子构象的定量关系.

The electron transport properties of diphenylacetylene molecular wires with various conformations were studied by the first-principles density functional theory （DFT） and the non-equilibrium Green function （NEGF） technique. The electron transport properties were discussed in terms of the spatial distributions of molecular orbitals and the transmission spectra of the molecular wires under various applied voltages. The results demonstrated that with the increase of molecular torsion, the LUMO-HOMO gap increased and transmission spectrum decreased. Under the influence of applied voltage, the HOMO and LUMO tended to move to low and high potential sides of the molecule, respectively. Current-voltage calculations revealed that the planar molecule was the most conductive. With the increasing torsional angle, the molecular conductance decreased and the perpendicular molecule conductance was the worst. Quantitative relationship between molecular torsion and molecular conductance was given.