SURFACE PHONONS OF D-SI(111)-(1X1)

In this short contribution we present and discuss the surface-phonon s pectrum and spectral densities for the deuterium-terminated Si(111)-(1 x1) surface. Our calculations, which are based on a semi-empirical tot al-energy approach, yield salient adsorbate- and substrate-induced vib rational modes. An analysis of these modes in comparison with previous results for H:Si(111)-(1x1) and H:C(111)-(1x1) turns out to be very r evealing, since D:Si(111)-(1x1) proves to be an interesting connecting link between the former two systems as far as surface vibrational pro perties are concerned. The physical origin of surface modes becomes pa rticularly transparent by relating them to the specifically different mass misfits between respective adsorbate and substrate atoms in the t hree systems.