(2x1) reconstruction and hydrogen-induced de-reconstruction of the diamond(100) and (111) surfaces

We present a comparative study of the (2 X 1) reconstruction of the (100) and (111) diamond surfaces, and of their hydrogen-induced de-reconstruction, using ab initio local-density-functional calculations. We show that whereas for the (111) surface the absorption of a monolayer of hydrogen stabilizes the (1 x 1) bulk-terminated surface, for the (100) surface the (2 X 1) surface structure remains stable (albeit with a strongly enhanced bond-length of the surface dimers). Results for the electronic surface-states are presented.