It was noted that, in GaN, an exceptionally important role was played by Ga-interstitials which were mobile at room temperature. Despite their rather large formation energy, they were observed in irradiated wurtzite-GaN. At least two similar, but clearly distinct optically detected electron paramagnetic resonance signals: L5 and L6/L6* were identified (via exceptionally large nearly isotropic hyperfine splittings of about 4GHz) as indicating interstitial Gai2+ in 2 different lattice configurations. However, judging from experimental data and total energy calculations alone, the exact microscopic configuration remained unclear. In this theoretical work, the situation was elucidated by means of ab initio calculations of the complete set of electron paramagnetic resonance parameters, hyperfine splittings as well as g-tensors, for the stable structural configurations of the Ga-interstitial, using a gauge-including projector augmented plane wave approach. Ga Self-Interstitials in GaN Investigated by ab initio Calculations of the Electronic g-Tensor. U.Gerstmann, A.P.Seitsonen, F.Mauri: Physica Status Solidi B, 2008, 245[5], 924-6