Stoichiometry and surface reconstructions of (001) surfaces of silicon carbide

The surface reconstructions of carbon and silicon terminated p(2 X 1) and c(2 X 2) (100) surfaces of cubic silcon carbide have been investigated using an ab initio DFT-LDA supercell approach. For the carbon atoms we use ultrasoft Vanderbilt pseudopotentials which allow the use of an extremely small plane-wave cutoff energy. Interactions due to an artificial electric field between the two inequivalent slab surfaces are avoided by saturating one (carbon terminated) side with hydrogens. The results for the carbon terminated surfaces compare well with experimental results, whereas there are discrepancies for the silicon terminated surfaces.