Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)
O 17.66: Poster
Montag, 26. März 2007, 17:30–20:30, Poster C
Effective interaction energies for the description of two dimensional alloys: calculation from experimental and density functional theory data — •Andreas Bergbreiter1, Harry E. Hoster1, Yoshihiro Gohda2, Axel Groß2, and R. Jürgen Behm1 — 1Institut für Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm — 2Institut für Theoretische Chemie, Universität Ulm, 89069 Ulm
The atomic distribution in two-dimensional, surface confined alloys can be approximately described by an Ising Hamiltonian based on pairwise and trio interactions. We show, how the effective interaction energies can be derived from atomic resolution STM images in an inverse Monte Carlo (IMC) approach. In addition, the total energy of ordered surface alloys can be calculated via density functional theory (DFT). Based on the energies for a number of unit cells with varied composition and internal geometry it is possible to derive a second set of ECIs in a least-squares approach, i.e., by simple matrix inversion, which can be compared to the one generated by IMC.