Diamond (111) and (100) surface: ab initio study of the atomic and electronic structure

Within the framework of density-functional theory in local-density approximation (DFT-LDA) we perform first-principles calculations for the atomic and electronic structure of diamond surfaces. The electron-ion interaction is described by a soft non-local carbon pseudopotential. For the C(100) surface we find a 2 × 1 reconstruction of symmetric dimers to be energetically favourable. For the C(111) surface we compare the surface energies of various reconstructions. In case of the single-bond (one-dimensional) 2 × 1 reconstructed cleavage face we find the π-bonded chain model to be lowest in energy, whereas at the triple-bond (three-dimensional) face a (√3 × √3)R30° adatom-like model is similar in energy to the 2 × 1 single-chain model. For the equilibrium geometries we determine band structures and ionization energies,