Two carbon atoms occupy the same tetrahedral site along the <100> direction. Both carbon atoms, threefold coordinated, have an unpaired electron and which lead to 2 possible spin states: singlet (Sz=0) and triplet (Sz=1). Click for the vibrational normal modes of the former spin state.
Vacancy and <100> self split-interstitial defects are now in the same system. Out of the many, 3 different mutual orientations are considered that lead to different defective structures: VI1, VI2S and VI2D defects. Click for further information about these 3 systems.
This defect consists of two vacancies that are third nearest neighbours. The six unpaired electrons lead to 4 different spin states: singlet (S2=0), triplet (S2=1), quintet (S2=2) and septet (S2=3), with the first being the most stable one. Click for the vibrational normal modes.