Hydrogenation of nanodiamond surfaces: Structure and effects on crystalline stability

Presented are results of our ab initio study of the surface reconstruction and relaxation of (100) surfaces on bulk and nanocrystalline diamond. We have used a density functional theory (DFT) within the generalized-gradient approximation (GGA) via the parallel computer version of the Vienna ab initio simulation package (VASP), to consider dehydrogenated and hydrogenated surfaces. Edges and corners of nanocrystals offer a new challenge in the determination of surface structure. We have applied the methodology for stepped diamond (100) surfaces to this problem, and consider it useful in describing nanodiamond edges and corners to first approximation. Our results also indicate that dimer lengths and atomic layer depths of the C(100)(2 x 1) and C(100)(2 x 1):H nanodiamond surfaces differ slightly from those of bulk diamond. The effects of these differences on crystalline stability are discussed, with the intension of offering a better understanding of the effects of nanodiamond surfaces on the stability of diamondoid nanostructures.