Surface diffraction structure determination from combinatorial simultaneous optimization

We present a technique to efficiently locate the global minimum of a cost function on a complex multi-dimensional parameter space (e.g. a structural reliability R-factor). The method builds a convergent series of structures from combinatorial simultaneous optimization of all the parameters on different subspaces of the experimental data base. Performance has been tested for two model situations: (1) phase retrieval from electron scattering by a single atom and (2) low-energy electron diffraction analysis of simulated I(V) curves for the Ir(1 1 0)-p(2 × 1) missing row. Compared under the same conditions, a reduction in the computation effort, is found w.r.t. previous state-of-the-art methods (e.g., simulated annealing and genetic algorithms).