It was recalled that a plausible (2 x 2) π-bonded-trimer structure had recently been found for the clean diamond (111) surface. By using the local-orbital density-functional molecular-dynamics method, this (2 x 2) structure was found to undergo phase transition, into the Pandey (2 x 1) π -bonded chain structure upon adsorbing H or Li. However, this surface did not undergo phase transition upon the adsorption of F or O at the same adsorption site. The results indicated that s-electrons played an important role in disrupting the sp2 bonding of the (2 x 2) structure.

M.H.Tsai, J.C.Jiang, S.H.Lin: Physical Review B, 1997, 56[19], 12127-30