Surface reconstruction and electronic properties of clean and hydrogenated diamond (111) surfaces

We present ab initio local-density-functional calculations of the structural and electronic properties of clean and hydrogenated diamond (111) surfaces with one and three dangling bonds (1db, 3db), respectively. For the clean 1db-surface we predict a (2 × 1) reconstruction with symmetric, very slightly buckled dimers at the surface, and a stronger buckling in the deeper layers. Hydrogenation leads to a complete de-reconstruction of the (111)-1db surface. For the 3db-surfaces we have performed a comparative study of the (2 × 1) and ( 3 × 3 ) reconstructions and find the (2 × 1) structure to have a slightly lower energy for both the clean and the hydrogenated surfaces.