We use ab initio local-density-approximation methods to study the electronic and geometrical structure of the various C(100) surfaces. The calculated densities of states suggest that the surface states observed for the (2×1) surface are attributable only to the clean C(100)(2×1), not the C(100)(2×1):H. The hypothetical C(100)(1×1):2H is found to be energetically unstable. The C(100)(3×1):1.33H is found to be favored over the C(100)(2×1):H. H desorption energies are calculated.

• Received 6 May 1993

DOI:https://doi.org/10.1103/PhysRevB.48.5261