New dimerized-chain model for the reconstruction of the diamond (111)-(2 × 1) surface

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.