Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 69: Poster: Spin Phenomena in Chiral Molecular Systems
O 69.2: Poster
Wednesday, March 20, 2024, 18:00–20:00, Poster C
Multi-scale simulation of structural motifs in assemblies of helical molecules — Kevin Preis1, •Sibylle Gemming1, Jeffrey Kelling1, and Florian S. Günther2 — 1Instute of Physics, TU Chemnitz, Chemnitz, Germany. — 2UNESP, Rio Claro, Brazil.
Helical polypeptide molecules sparked interest as candidate materials for studying spintronic effects on the nano-scale. As charge carriers are transmitted through assemblies of helical molecules, spin polarization of the transmitted current has been detected by scanning tunneling spectroscopy and attributed to a polarization dependent tunneling resistance or a spin-selective propagation along the backbone of the helical molecule. For single molecules there is, however, debate, whether the helical symmetry break alone or also the adsorption-induced surface polarization for films on metallic substrates decisively influences the polarization direction [1]. The present simulations, address potentially beneficial effects of aggregate formation from helical molecules depending on the type of helicity, the orientation on the surface and the type and strength of the molecule-surface interaction. For poly-alanine (PA) we studied the lateral*ordering between PA homo- and heterochiral pairs by van-der-Waals-corrected DFT-based tight binding calculations. Denser packing geometries can be reached by heterochiral PA pairs. Furthermore, coarse-grained classical potentials were derived from the DFTB data, and the different PA phases seen in STM were also successfully obtained from Monte-Carlo simulations. [1] Aragones et al., small 2017, 13, 1602519.