The (5 x 2) reconstruction of the (001) β-phase surface was investigated by using an ab initio pseudopotential method with a Gaussian basis set. By comparing the grand canonical potential for a number of possible structural models, a 2-adlayer asymmetrical-dimer model was found to be the most stable. This model was similar to the one which had been previously suggested for the (3 x 2) surface. In this model, 2 adlayers of Si atoms - both with coverages of less than one – were adsorbed on the clean Si-terminated surface. The lower of these adlayers contained 3/5 of a monolayer and the upper layer contained 1/5 of a monolayer of Si adatoms. The total coverage of Si adatoms was therefore 4/5. By minimizing the total energy, it was found that asymmetrical dimers formed in both adlayers. These gave rise to a rich spectrum of surface bands. The calculated filled-state scanning tunnelling microscopic images exhibited a bright oval spot in each (5 x 2) unit cell. This was consistent with experimental observations.

Ab Initio Studies of the β-SiC(001) -(5 x 2) Surface W.Lu, P.Krüger, J.Pollmann: Physical Review B, 2000, 61[4], 2680-7