Surface Phonons in Si(111) 2 × 1: Folding and Chain Effects of the Reconstruction

In the present paper we report a slab calculation of the surface phonon dispersion curves for Si(111) 2 × 1 in the framework of the Bond Charge Model dynamics. Our results are in very good agreement with the existing experimental data and provide an interpretation for the dynamical structures of this surface, based on the relationship with the unreconstructed one. This latter perspective stands in opposition to a recently published analysis, which points out the uniquity of the chain dynamics, and comparison is made between the two on the grounds of the experimental information.