the formation of chemiacl bonds in the ovito

Please reply to the entire list, not just to me. That way other people can see how problems are fixed, too.

Like I said, in Ovito you can specify per atom type the cut-off distance for drawing bonds. If you set those values to the right ones for Si and C atoms, then everything should work out fine, if nothing else went wrong with your simulation. What the right values for the cut-off are is up to you to decide.