Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 35: Organic-inorganic hybrid systems and organic films IV

O 35.6: Talk

Tuesday, March 13, 2018, 15:15–15:30, MA 042

Influence of Molecule Size on Surface Polymorph Formation — •Andreas Jeindl, Michael Scherbela, Lukas Hörmann, and Oliver T. Hofmann — Institute of Solid State Physics, Graz University of Technology, Austria

Many properties of thin films, such as solubility or conductivity, are determined by the polymorph they assume upon adsorption on the (metal) substrate. In order to engineer functional interfaces, it is therefore imperative to understand and predict which polymorphs form for a given material combination. Yet, there are surprisingly few systematic studies that allow to deduct authoritative relationships between the molecular structure and the interface polymorph that will form. Computational studies are hindered by the intractably vast number of possible polymorphs, also known as 'configurational explosion'.

In this talk, we systematically investigate the influence of molecule size on the formation of surface polymorphs on the example of acenequinones on Ag(111). We present the SAMPLE approach that combines a physically motivated coarse-graining of the potential energy surface with machine learning as a method to overcome the configurational explosion. Precomputing the electrostatic and van-der-Waals interaction between adsorbate molecules allows us to extend the applicability of the method from model systems to technologically relevant molecules, such as acenequinones. For this example, we discuss the impact of the molecule size on the relative energies of selected polymorphs and the propensity to form low-energy defects.