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O: Fachverband Oberflächenphysik

O 13: Organic Molecules on Inorganic Substrates: Adsorption and Growth

O 13.9: Vortrag

Montag, 17. März 2025, 17:00–17:15, H8

Supercharging Polymorphism of Organic/Inorganic Interfaces — •Christoph Wachter and Oliver T. Hofmann — Institute of Solid State Physics, Graz University of Technology, Graz, 8010, Austria

The polymorphism of organic/inorganic interfaces heavily influences a multitude of their properties. Therefore, altering the polymorphism by changing the substrate or modifying the intermolecular interactions has been studied extensively. However, the extent to which charge transfer affects polymorphism has yet to be investigated systematically. Based on the hypothesis that there is a link between the band width of polymorphs and their relative energy, we expect that polymorphs with larger band width are preferred if charge is transferred uniformly across the organic monolayer.

Conversely, it is also possible for charge to localize in individual adsorbates instead of spreading out across the monolayer. Such localized charge transfer occurs when the electronic coupling of the organic molecules to each other and to the substrate is small. In that case the relation stated above is not well-defined anymore.

To investigate the impact of both localized and delocalized charge transfer on polymorphism, we employ density functional theory in conjunction with a machine-learning based structure search algorithm. To properly capture charge localization, we go beyond the standard semi-local functionals by utilizing hybrid functionals and report whether the expected relation still holds in the case of localized charge transfer.

Keywords: charge transfer; surface polymorphism; structure prediction; density functional theory; machine learning