English: Structure of dumbbell self-interstitial in silicon; note that the dumbbell atoms are not centered on the perfect lattice site. The structure of the interstitial in Si may depend on charge state and doping level of the material, and some of these are believed to have other structures. Kai Nordlund, originally made for docent lecture in 1998 with FrameMaker, text changed to English in 2007 with gimp.