Similar Building Blocks, Diverse Structures: Understanding Self-Assembly of Acenequinones on Ag(111)

The ongoing miniaturization in nanotechnology raises the need to understand (and control) the formation of surface polymorphs on a molecular level. Due to the intricate interaction mechanisms, complex physics and high configurational complexity at play, this understanding is still at the very beginning.
In this contribution, we showcase and explain the surprisingly diverse experimental surface monolayers a homologous series of acenequinones forms on Ag(111).^[1] Using a newly created tool^[2] that combines coarse graining, DFT and machine learning, we are able to predict the motifs that form. Our step-by-step analysis identifies three important driving forces governing the motif formation: i) interactions between adsorbates and substrate favoring specific orientations and adsorption sites; ii) intermolecular interactions favoring the formation of close packed structures; and iii) steric hindrance partly blocking otherwise beneficial molecular arrangements.
This shows that, using the right techniques, one can gain fundamental insight even for such complex systems, adding a new tool to nanotechnology design.

[1] Jeindl et al., arXiv:2010.10347
[2] Hörmann et al., Comp. Phys. Comm. 244, 2019