Efficient Scheme for Calculation of Low-Energy Electron-Diffraction Intensities in the Presence of Large Superlattices, with Application to the Structural Analysis of Benzene Adsorbed on Rh(111)
A powerful calculational low-energy electron-diffraction scheme is introduced for superlattices with unit cells of any size: beam-set neglect. It is applied in the first structural analysis from low-energy electron-diffraction intensities of a large molecule, benzene, adsorbed on a single-crystal metal surface, Rh(111). In a ( /sub 13//sup 31/) lattice, benzene is found to lie flat on the surface, centered over hcp-type hollow sites. A planar, possibly distorted C/sub 6/ ring is found with Rh--C bond lengths of 2.35 +- 0.05 A.