Quantum transport calculations are conducted using nonequilibrium Green’s functional formalism to study the effect of halogenation on the electronic transport properties of aromatic S(C${}_6$H${}_5$)${}_2$X and alkanethiolate S(CH${}_2$)₁₁X molecules (with X = H, F, Cl, Br, or I) sandwiched between gold electrodes. In terms of conductance, both molecules show the same dependence on the halogen terminal groups despite their different electronic nature. For example, fluorination results in a reduction of the current by almost an order of magnitude, whereas iodine substitution leads to larger current as compared to the reference system (i.e. hydrogen termination). Regarding the asymmetry in the current–voltage characteristics, halogenation reduces the rectification level for the aromatic molecule with the smallest asymmetry for iodine termination. However, in the case of alkanethiolate molecule, halogen substitution increases the current rectification except for fluorination. A physical explanation of these results is obtained from the analysis of the behavior of the density of states, transmission spectra and transmission eigenstates. These findings are of practical importance in exploring the potential of halogenation for creating functional molecular self-assemblies on metallic substrates.

使用非平衡格林泛函形式进行量子输运计算，以研究卤化对芳族 S (C${}_6$H${}_5$)${}_2$X 和烷硫醇盐 S (CH${}_2$) _{11 个}X 分子（X = H、F、Cl、Br 或 I）夹在金电极之间. 就电导而言，尽管两种分子的电子性质不同，但它们对卤素末端基团的依赖性相同。例如，氟化导致电流减少几乎一个数量级，而与参考系统（即氢终止）相比，碘取代导致更大的电流。关于电流 - 电压特性的不对称性，卤化降低了芳族分子的整流水平，其中碘终止的不对称性最小。然而，在烷硫醇分子的情况下，卤素取代增加了除氟化之外的电流整流。这些结果的物理解释是通过对状态密度、透射光谱和透射本征态的行为的分析获得的。