Density functional theory methods have been used to examine the intera
ction of (i) the carbene and C-2 tools With a pair of radical sites on
the diamond (111) surface and (ii) the carbene tool with a surface di
mer on the reconstructed diamond (100) surface. For the (111) surface,
the carbene tool (carbenecyclopropene) is found to bond preferentiall
y to a single radical site (on top site) rather than at a bridged site
. This means this tool is not useful for adding a carbon to diamond (1
11) at this site. The C-2 tool, on the other hand, is found to add a b
ridged C-2 molecule, through a series of steps which are overall exoth
ermic. The carbene tool can add a carbon to the bridged C-2 molecule,
leading to a bridged C-3 molecule perpendicular to the surface, by an
overall exothermic series of steps. If another radical site is activat
ed, the C-3 can bend over to a threefold coordinated position, with on
ly a small barrier. Thus, this series of steps can be used to create a
threefold coordinated C-3 molecule on the diamond (Ill)surface. For t
he surface dimer on the reconstructed (100) surface, the carbene tool
is found to add with no barrier if the angle between the tool and the
surface is allowed to vary or with a 0.09 aJ (13 kcal mol(-1)) barrier
for a C-2 upsilon constrained approach. In this case, a bridged site
is strongly favored, and the subsequent steps of sequentially breaking
the pi and sigma bonds between the tool and added carbon atom are all
feasible. Thus, this series of steps can add a bridged C atom to the
reconstructed diamond (100) surface.