Structural parameters and energy have been calculated for C1-3 and C-9 clusters using density functional theory through the deMon program. The C1-3 clusters were fully optimized using deMon
different basis sets were tested in order to choose the suitable one to be used in the C-9 clusters. In the case of C-2 the results were compared with experimental values. DZVP2 basis was selected because it always gave the closest value to the experimental data. The C-9 carbon clusters were designed in relation to C(100) diamond surface. The energies of the nonrelaxed and relaxed surfaces with and without hydrogen were calculated. in the same way CH3-relaxed and CH2-relaxed species were calculated. The diamond growth mechanism proposed in the literature was evaluated by an energy analysis. The C-CH3 distance is reported. (C) 1997 John Wiley & Sons, Inc.