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O: Fachverband Oberflächenphysik

O 87: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures V

O 87.5: Vortrag

Donnerstag, 15. März 2018, 11:45–12:00, MA 004

Characterization and prediction of peptide structures on inorganic surfaces — •Dmitrii Maksimov, Carsten Baldauf, and Mariana Rossi — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

Interfacing biological molecules with inorganic materials can give access to new technology that joins the versatile character of the biomolecular world with the robust electronic properties of inorganic materials. Peptides, for example, present a large degree of modularity, chemical versatility and conformational adaptability. However, their high degree of conformational freedom makes it a challenge to be able to predict structural motifs and understand the physics governing them. Here we address the structure-search problem by extending a first-principles genetic algorithm package that works on internal degrees of freedom [1] in order to include the position and orientation of molecules with respect to the surface. We show that energy differences between different conformations of the flexible ArgH⁺ amino acid on Cu(111) show significant discrepancies when optimized with a force-field (tailored for peptide-surface interactions [2]) and with dispersion-corrected DFT. We further show that the excess charge of the protonated ArgH⁺ is efficiently screened upon adsorption on metallic surfaces and that the Arg amino acid adopts a zwitterionic conformation on Cu(111) which considerably increases the molecular dipole parallel to the surface. [1] A. Supady, et al., JCIM 55, 2338 (2015) [2] F. Emami, et al., Chem. Mat. 26, 2647 (2014).