In the experimental He atom scattering time-of-flight spectra of rhodium covered with hydrogen there is no evidence of the anomalous high intensity of the resonant mode present in the clean surface. In this paper we explain the different behaviour of clean and covered rhodium (111) surface in terms of the "corrugating" effect of the electron density of hydrogen atoms. For clean surface the surface electronic density is shifted with respect to the lattice atomic positions, i.e. there is an "anticorrugating" effect that enhances the intensity of the longitudinal resonant mode which becomes dominant for some scattering geometries. For the covered surface the hydrogen atoms remove the anticorrugation, the charge profile becomes corrugated and the intensity of the longitudinal resonant vibrational mode remains very weak with respect to the Rayleigh wave intensity.
Dynamical properties of Rh(111):H(1x1) surface / Santoro, Giorgio; Franchini, Anna; Bortolani, Virginio. - In: NUOVO CIMENTO DELLA SOCIETÀ ITALIANA DI FISICA. D CONDENSED MATTER, ATOMIC, MOLECULAR AND CHEMICAL PHYSICS, BIOPHYSICS. - ISSN 0392-6737. - STAMPA. - 20:(1998), pp. 1055-1058.