Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 98: Organic Molecules on Inorganic Substrates VII

O 98.5: Vortrag

Freitag, 5. April 2019, 11:30–11:45, H17

Surface polymorph formation explained: Acenequinones on Ag (111) — •Andreas Jeindl, Lukas Hörmann, Alexander T. Egger, and Oliver T. Hofmann — Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Austria

Understanding (and modifying) the formation of surface polymorphs is still not straightforward, as it is hardly known why specific structures form. Experimental studies are hindered by the huge thermodynamic search space and kinetic trapping. Computational studies, on the other hand, are hampered by the so-called ’configurational explosion’.

In this contribution, we computationally investigate the formation of surface polymorphs for a homologous series of acenequinones on Ag (111). We perform a comprehensive structure search utilizing the SAMPLE[1,2] approach, which combines a physically-motivated coarse graining of the potential energy surface with machine learning to overcome the configurational explosion.

Contrary to most machine learning methods, which rely on mere statistical correlation, our approach gives valuable physical insight into the systems of interest. We investigate the interactions of low-energy polymorphs, distinguishing between inter-molecular and molecule-surface interactions. For further insight, we map the interactions onto different parts of the molecules, which allows us to identify the main contributors of polymorph formation. This could serve as a first step towards establishing rules for a systematic design of surface layers.

[1] Hörmann et al., arXiv:1811.11702

[2] Scherbela et al., Phys. Rev. Materials 2, 043803