Effect of van der Waals interactions in the DFT description of self-assembled monolayers of thiols on gold
authors Fajin, JLC; Teixeira, F; Gomes, JRB; Cordeiro, MNDS
editors RuizLopez, MF; DelValle, FJO
nationality International
journal 9TH CONGRESS ON ELECTRONIC STRUCTURE: PRINCIPLES AND APPLICATIONS (ESPA 2014)
author keywords Gold (111) surface; Thiols; Periodic density functional theory; van der Waals effects
keywords SCANNING-TUNNELING-MICROSCOPY; MOLECULAR-DYNAMICS SIMULATION; DENSITY-FUNCTIONAL THEORY; TOTAL-ENERGY CALCULATIONS; AUGMENTED-WAVE METHOD; AU(111) SURFACE; ALKANETHIOL MONOLAYERS; HEXADECANETHIOL MONOLAYERS; 1ST PRINCIPLES; STRIPED PHASE
abstract The structure and energetic properties of self-assembled monolayers (SAMs) of alkanethiol derivatives (simple alkanethiols, mercaptoalkanoic acids and aminoalkanethiols with different chain length) adsorbed on the metallic Au(111) surface are investigated through periodic DFT calculations. To sort out the effect of van der Waals (vdW) interactions on the DFT calculations, the results of the standard GGA-PBE functional are compared with those obtained with approaches including the vdW interactions such as those incorporating the Grimme's (GGA-PBE-D2) and the Tkatchenko-Scheffl er's (GGA-PBE-TS) schemes, as well as with the optB86b-vdW density functional. The most significant difference between the two sets of results appears for the adsorption energies per thiol molecules: The standard functional predicts energy values 30-40 % lower than those obtained when the van der Waals interactions are taken into account. This is certainly due to a better description of the lateral interactions between the chains of the thiols when including the van der Waals effects. Differences are also found between the adsorption energies predicted by density functionals taking into account the vdW corrections, with values increasing in the order GGA-PBE-D2 < GGA-PBE-TS < optB86b-vdW. Furthermore, the functionals considering dispersion interactions favor much more tilted orientations of the SAMs over the surface with respect to those found using the standard GGA functional (the SAMs' tilt angles increase from 17 degrees-24 degrees to 37 degrees-46 degrees), being the former in closer agreement with available experimental data. In contrast, the SAMs' precession angle and monolayer thickness are less affected by the type of DFT exchange-correlation functional employed. In the case of low surface coverage, the chains of the thiols adopt more tilted configurations and tend to lay side-down onto the surface.
publisher SPRINGER-VERLAG BERLIN
issn 2194-8666
isbn 978-3-662-49221-5; 978-3-662-48793-8
year published 2016
volume 11
beginning page 127
ending page 139
digital object identifier (doi) 10.1007/s00214-015-1666-y
web of science category Chemistry, Physical
subject category Chemistry
unique article identifier WOS:000378835900013

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