FITTING DOZENS OF COORDINATES BY LEED - AUTOMATED-DETERMINATION OF COMPLEX SURFACE-STRUCTURES

We present the first comprehensive discussion of automatic optimization procedures for surface-structure determination by LEED. These procedures combine numerical search algorithms with efficient methods of determining the diffracted intensities for varying structures. Such approaches can reduce the computer time required for an entire structure determination by many orders of magnitude, while fitting many times more unknown structural parameters. Thereby, relatively complex structures, with typically 10 adjustable atoms (or 30 adjustable coordinates), can be readily determined on today's workstations. We list over two dozen structures so determined, many as yet unpublished.