Abstract
Surface and subsurface mean-square displacements (MSD) are calculated in the classical limit on the dimerised (001)-(2*1) surface of C, Si and Ge crystals. A method of the self-consistent Einstein model is applied to the Appelbaum and Hamann symmetric dimer model. The MSD of surface atoms parallel to the dimer bond is found to be reduced by an order of magnitude in Si and Ge compared to that without reconstruction. Sub-surface MSDs of atoms at pedestal sites are distinct from those at cave sites.