Structural, electronic, and vibrational properties of diamond (100), (111), and (110) surfaces from ab initio calculations

Using a first-principles technique, we calculate the structural, electronic, and vibrational properties of the (100), (111), and (110) surfaces of diamond. Stable (2×1) and Pandey chain reconstruction were found for the bare (100) and (111) surfaces, respectively. The surface zigzag chain of the (110) face is buckled and accompanied by a small charge transfer between the surface atoms. Hydrogen adsorption on these surfaces is energetically favorable. The electronic structures of the unhydrogenated surfaces show gap states which disappear upon termination of the surfaces with H atoms. Simulated scanning tunneling microscopy images are also presented. Vibrational modes involving excitations of the surface dimers and chains were identified for the clean surfaces, while phonon modes associated with H stretching and H bending motions wer found for the hydrogenated surfaces.