Measurements of surface phonon frequencies on Al(110) for comparison with recentab initiocalculations

High-resolution He-atom time-of-flight spectroscopy has been used to measure the dispersion curves of surface phonons on Al(110) in the two high-symmetry directions out to the zone boundaries. The experimental frequencies are compared with the results of the recent pseudopotential calculation of surface forces by Ho and Bohnen [Phys. Rev. Lett. 56, 934 (1986)]. The largest difference between experiment and theory is at X̄ where the experiment is smaller by 15%.