GEOMETRIC STRUCTURE OF BE(10(1)OVER-BAR-0)

The structure of clean Be(<10(1)over bar 0>) was determined by low-ene rgy electron-diffraction (LEED) I(V) analysis and the result compared to first-principles calculations. Both theory and experiment indicate that from the two possible terminations of the truncated bulk, the one with the shorter first-interlayer spacing is realized. The values for the multilayer relaxations obtained by LEED essentially coincide with the theoretical prediction. Although the magnitude of the first- to s econd-layer relaxation fits well into the trend observed on other simp le metal surfaces, the driving force is probably different for berylli um.