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DS: Fachverband Dünne Schichten
DS 13: Poster
DS 13.7: Poster
Donnerstag, 20. März 2025, 18:00–20:00, P1
Simulation of self-assembled polyalanine α-helices films: Development and application of an empirical potential — Kevin Preis1, Hadis Ghodrati Saeini1, Christoph Tegenkamp1, Sibylle Gemming1, Jeffrey Kelling2, and •Florian Günther3 — 1Technische Universität Chemnitz, Chemnitz, Germany — 2Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 3São Paulo State University, Rio Claro, Brazil
Polypeptide molecules have been discussed as potential candidates for electronic spin-filters because of the so-called chiral-induced spin selectivity. For this reason, tremendous effort is invested to characterize the structural and electrical properties of self-assembled monolayers (SAMs) of peptide helices, e.g. polyalanine (PA) α-helices. In our work, we aim at characterizing the intermolecular interactions that govern the formation of PA-SAM films. For this, we elaborated an empirical potential that models the interaction of two isolated helices using the density functional based tight-binding method. With these potentials, energetically most favored arrangements in SAM films were simulated via a Monte-Carlo approach using the simulated annealing and the Metropolis algorithm. Statistically analyzing the relative positioning of adjacent molecules, we are able to classify the degree of frustration in SAM films. For enantiopure systems, we found that a frustration-free arrangement is possible yielding a perfect hexagonal lattice. For mixtures of different chiralities, parallel aligned domains of differently handed helices were obtained. Both of these observations are in great agreement to experimental works.
Keywords: self-assembly; polyalanine alpha-helices; Monte Carlo simulation