The problem addressed here can be concisely formulated as follows: given a stable surface orientation with a known reconstruction and given a direction in the plane of this surface, find the atomic structure of the steps oriented along that direction. We report a robust and generally applicable variable-number genetic algorithm for step structure determination and exemplify it by determining the structure of monatomic steps on Si(114)-2× 1. We show how the location of the step edge with respect

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... to the terrace reconstructions, the step width (number of atoms), and the positions of the atoms in the step region can all be simultaneously determined.