H-INDUCED AND LI-INDUCED (2X2)-TO-(2X1) PHASE-TRANSITIONS ON DIAMOND C(111)

Recently, Tsai, Jiang, and Lin have found a plausible (2x2) pi-bonded- trimer structure for the clean diamond C(111) surface. Using the local -orbital density-functional molecular-dynamics method, this (2 x 2) st ructure is found to undergo phase transition into the Pandey's (2x1) p i-bonded chain structure with the adsorption of H or Li. However, this surface does not undergo phase transition with the adsorption of F or O for the same adsorption site considered. These results indicate tha t s electrons play an important role in disrupting the sp(2) bonding o f this (2x2) structure.