Of the relaxed, graphitic, buckled, and $\pi$-bonded-chain-type models for the diamond (111)-(2 × 1) surface, only the chain model appears to account for the measured surface-band dispersion. The interaction of dangling orbitals which determines the dispersion is large in the chain model because only in this model are the dangling bonds located on nearest-neighbor atoms. The data also suggest a dimerization of the chains.

• Received 4 January 1982

DOI:https://doi.org/10.1103/PhysRevB.25.4338