+The influence of Si self interstitials on the diffusion of a single carbon atom is displayed in Fig. 3.
+Diffusion coefficients for different amount of Si self interstitials are shown.
+A slight increase is first observed in the case of 30 interstitial atoms.
+Further increasing the amount of interstitials leads to a tremendous decay of the diffusion coeeficient.
+Generally there is no long range diffusion of the carbon atom for a temperature of $450\, ^{\circ} \textrm{C}$.
+The maximal displacement of the carbon atom relativ to its insertion position is between 0.5 and 0.7 \AA.