The energetics and structures of physisorbed and chemisorbed alkanethiols on Au(111) have been systematically investigated up to 10 carbon atoms using van der Waals (vdW) corrected density functional theory (DFT) calculations. The role of chain length, tilting angle and coverage on the adsorption characteristics has been examined to elucidate the energetics and plausible transformation mechanisms between lying down and standing up phases. Coverage and size dependent chain-chain electronic interactions counteract with the alkyl chain-gold surface interactions and the surface relaxation of the metal in the formation of standing up monolayer structures. For the striped phases of long chain alkanethiols, however, our calculations on decanethiol indicate alkyl chain-gold surface interactions to be strong enough to force the molecule to be perfectly parallel to the surface by lifting a gold atom up, in agreement with the proposed models for this film in the literature.

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Graphene adsorption on Au(111) surface was explored to identify their common surface structures by means of van der Waals corrected density functional theory calculations. The alignment of graphene in the form of certain rotational angles on the gold surface has an important role on the lattice matching which causes Moiré patterns, and on the electronic properties of the resulting common cell structures. The dispersive weak interactions between carbon and gold layers lead to a downward shift of Fermi energy of the adsorption system with respect to the Dirac point of graphene showing a p-type doping character. Moreover, the shift was shown to depend on the rotational angle of graphene on Au(111). arXiv:1909.03652v1 [cond-mat.str-el]

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Positional isomers of dicarba-closo-dodecaboranethiols with various functional groups (−NO2, −CHO, −CONH2, −F, −Cl, and −OH) were considered on Au(111) forming (3 × 3) and (5 × 5) structures. Dispersion corrected density functional theory calculations reveal the influence of functional groups on the adsorption characteristics of these carboranethiols depending on the coverage. Functionalized molecules not only possess fascinating chemical and electronic properties but also show stronger chemisorption profiles on gold in relation to the pristine precursors. Molecular dipole moments which can be modified by functional groups were found to be effective in tunability of the work function of deposited surfaces. Results indicate that densely packed adsorption geometries in which functional groups lean toward back of adjacent molecules allowing H-bonding are energetically favorable and enhance stability and ordering of constituents in self-assembled monolayers. Carboranethiols with functional groups are promising to enrich the surface electrochemical properties of resulting surfaces.