Ab initio structural characterization of a hydrogen-covered diamond (001) surface -: art. no. 125423

The structural characterization of a hydrogen-covered diamond(001) surface has been investigated by density-functional theory with the plane-wave pseudopotential method and the generalized gradient approximation. Structures with different hydrogen coverage, from one to two monolayers, are considered. The formation energy of different phases is analyzed as a function of hydrogen chemical potential mu(H). As mu(H) increases, the (2x1):H phase, (2x2):1.5H trough phase [or (3x1):1.33H phase for a smooth surface], and the canted (1x1):2H phase each successively become the most stable phase. The phase proposed by us, the (2x2):1.5H trough surface phase, exists over a wide range of chemical potential, and can be expected to be found in experiments.