Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 14: Metal substrates: Adsorption of organic / bio molecules II

O 14.3: Vortrag

Montag, 22. März 2010, 15:30–15:45, H36

Simulation of short-range order in a metal-organic network — •Harry E. Hoster, Achim Breitruck, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany

Short-range order (SRO) is a common phenomenon for surfaces and adlayers, where disturbances of a periodically ordered ground state are energetically inexpensive and thus thermally accessible. It has become common to simulate SRO using Monte-Carlo approaches based on additive models for the structure relevant interactions. The necessary parameters are usually obtained from ab-initio calculations or from fitting to experimental data. In this contribution, we will demonstrate that adlayers involving large organic molecules may exhibit a SRO with many similarities to disordered two-dimensional alloys [1]. Specifically, we focus on a structure that consists of a mixture of metal-organic complexes and organic trimers distributed on a hexagonal lattice. This distribution reflects an SRO governed by hydrogen bonds between the different types of lattice occupants. We show that this SRO, which is directly observed by scanning tunneling microscopy, can be simulated using pairwise interaction energy parameters based on a simple counting of hydrogen bonds [2].
[1] A. Bergbreiter et al., Phys.Chem.Chem.Phys. 9, 2007, 5127.
A. Breitruck et al., J.Phys.Chem.C Letters, DOI: 10.1021/jp908748w.