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O: Fachverband Oberflächenphysik

O 12: Morphology Prediction at Interfaces

O 12.3: Vortrag

Montag, 7. März 2016, 15:30–15:45, S051

Exploring the Electronic and Vibrational Properties of Disordered TCNE on Cu(111) Using a Basin Hopping Algorithm — •Veronika Obersteiner, Egbert Zojer, and Oliver T. Hofmann — Instiute of Solid State Physics, NAWI Graz, Graz Univeristy of Technology, Austria

While to date most first-principle studies focus on highly ordered crystalline materials, in this work we concentrate on the theoretical investigation of amorphous or disordered materials that are commonly used in experimental applications. To sample the complex potential energy surface (PES) of disordered organic/inorganic interfaces we develop a three-step geometry search algorithm based on Basin Hopping (BH) in conjunction with dispersion-corrected Density Functional Theory. First, we determine the local adsorption structures, then we coarse-grain the PES as a superposition of these local adsorption structures to finally efficiently jump between the locally optimized configurations using the BH algorithm.

Applying this approach to TCNE (tetracyanoethene) on Cu(111) we evaluate a set of energetically lowest lying structures, reflecting the distribution of local conformations and their environment. Our investigations reveal that at finite temperature a noticeable amount of TCNE molecules are bound in an upright standing manner to the Cu(111) surface, although this is not the global minimum. The different adsorption conformations exhibit very different electronic properties characterized by the charge states of the TCNE molecules and their vibrational spectra.