Global optimization in LEED structure determination using genetic algorithms

By application of search algorithms, low energy electron diffraction (LEED) structure determination is now capable of solving relatively complicated systems. However, since LEED is a diffraction technique, the danger remains in identifying an incorrect structure because a local rather than a global minimum in the R-factor hypersurface was found. Recently it has been suggested that simulated annealing could be employed to circumvent this potential problem. In this Letter, using the Ir(110)-(1 x 2) missing row structure as an example, we demonstrate that genetic algorithms can also be used for a full structural analysis. Our results indicate that a rough global search using a genetic algorithm, followed by structural refinement using conventional steepest descent methods, should yield the correct structure within a typically tractable timescale.