The morphological and electronic properties of isolated and monolayer phases of carboxyl- and amine-functionalized carboranethiols on unreconstructed Au(111) were determined using density functional theory calculations including van der Waals interactions. The groups are effective in the assembly of pristine adlayers on gold and also offer functionality when exposed at the SAM-environment interface. Anisotropy brought by both functional groups increases tilting of carboranethiols relative to the surface normal and absolute values of the dissociative chemisorption energies. Positional isomerization and the functional groups modify the molecular dipole moments which influence the adsorption characteristics. Even though carboxylic acid and amine groups have different chemical properties, they have similar effects on the adsorption characteristics of carboranethiols. Dense packing favors intermolecular interactions which gives a stronger binding relative to isolated adsorption. The carboranethiols with the functional groups can be arranged in the same lateral direction or in a dimer conformation with molecules facing each other. Carboxyl and amine groups offer functionalization of carboranethiol SAMs and in conjunction with positional isomerization shift tunability ranges of the work function of gold to higher energies.

中文翻译：

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Au（111）上的羧基和胺官能化的碳硼烷硫醇SAM：分散校正的密度泛函理论研究

使用包括范德华相互作用在内的密度泛函理论计算确定了羧基和胺官能化碳硼烷硫醇在未重构Au（111）上的分离相和单层相的形态和电子性质。这些基团可有效地在金上组装原始的adlayer，并且在SAM-环境界面暴露时也可提供功能。两个官能团带来的各向异性增加了碳硼烷硫醇相对于表面法向和解离化学吸附能的绝对值的倾斜。位置异构化和官能团修饰影响吸附特性的分子偶极矩。即使羧酸和胺基具有不同的化学性质，它们对碳硼烷硫醇的吸附特性有相似的影响。密集堆积有利于分子间的相互作用，相对于分离的吸附，分子间的相互作用更强。具有官能团的碳硼烷硫醇可以以相同的横向方向排列或以分子彼此面对的二聚体构型排列。羧基和胺基团提供了碳硼烷硫醇SAM的功能化，并结合了金的功函数向更高能量的位置异构化转移可调范围。