Atomic structure of Si{111}(3 × 3) R30°-Au

A low-energy electron-diffraction experiment and a quantitative intensity analysis find that among the many models reported in the literature for the Si{111} 3 × 3 R30°-Au structure, the one proposed by the total-energy calculations of Ding, Chan, and Ho is the only one that fits the experimental data satisfactorily. The crucial elements of this model are the absence of the first Si layer, a feature which was found by ion-scattering experiments, the size of Au trimers, which was determined by x-ray diffraction, and the Au-Si interlayer distance, which was suggested by the total-energy calculations. © 1992 The American Physical Society.