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首页> 外文期刊>Physical review >First-principles study of 1,4-butanedithiol molecules and radicals adsorbed on unreconstructed Au(111) and Au(100)
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First-principles study of 1,4-butanedithiol molecules and radicals adsorbed on unreconstructed Au(111) and Au(100)

机译：第一原理研究1,4-丁二硫醇分子和自由基在未重构的Au（111）和Au（100）上的吸附

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Ongoing experimental research effort is devoted to further the understanding of the adsorption of dithiol molecules on gold surfaces with promising technological applications. To elucidate the subject from a theoretical perspective, we study the submonolayer adsorption of 1,4-butanedithiol molecules and radicals on the unreconstructed Au(111) and Au(100) surfaces using density-functional theory. From the calculated local energy minima the lowest-energy configurations are selected. The alkane chains are roughly parallel to the surface, such that two sulfur-gold adsorbate-substrate bonds can form. On the unreconstructed Au(100) surface dissociation of butanedithiol molecules into H_2 in the gas phase and butanedithiol radicals chemisorbed on the surface is energetically preferred. The two sulfur atoms of the radical adopt hollow-bridge-like positions. On the unreconstructed Au(111) surface the S-H bonds are predicted to be cleaved due to entropic effects. In the ground-state configuration the two sulfur atoms of the butanedithiol radical adopt an fcc hollow and an fcc hollow-bridge position on the surface. Hence, we expect butanedithiol radicals to be the prevailing adsorbed species on both investigated gold surfaces. STM-images of the ground-state configuration of butanedithiol radicals chemisorbed on Au(111) have been simulated within the Tersoff-Hamann model. They show elongated bright features above the location of the alkane chain. The long axis is slightly tilted with respect to the (1 To) directions. Finally, a semiempirical approach has been evaluated to investigate the effect of van der Waals interactions to the binding energies calculated within GGA-DFT.
机译：正在进行的实验研究致力于以有前途的技术应用进一步了解二硫醇分子在金表面的吸附。为了从理论角度阐明该主题，我们使用密度泛函理论研究了未经重构的Au（111）和Au（100）表面上1,4-丁二硫醇分子和自由基的亚单层吸附。从计算出的局部能量最小值中选择最低能量配置。烷烃链大致平行于表面，因此可以形成两个硫-金吸附物-底物键。在未重建的Au（100）表面上，丁二硫醇分子在气相中解离为H_2，并且在能量上优选化学吸附在表面上的丁二硫醇自由基。自由基的两个硫原子采用空心桥状的位置。在未重构的Au（111）表面上，S-H键预计会由于熵效应而断裂。在基态构型中，丁二硫醇基团的两个硫原子在表面上具有fcc空心和fcc空心桥位置。因此，我们期望丁二酚自由基成为两个研究金表面上普遍存在的吸附物种。在Tersoff-Hamann模型中模拟了化学吸附在Au（111）上的丁二硫醇自由基基态构型的STM图像。它们在烷烃链的位置上方显示出细长的明亮特征。长轴相对于（1 To）方向略微倾斜。最后，已对半经验方法进行了评估，以研究范德华相互作用对GGA-DFT中计算的结合能的影响。

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