Fig. 1
a Kohn–Sham orbitals and levels of the SiV(0) defect in its |3A2g〉 ground state and its four excited state single determinants, as obtained from ab initio density functional theory (DFT) calculations. The geometry of the system is constrained to D3d symmetry, thus these electronic configurations correspond to the undistorted X = 0 configurational coordinate in Fig. 3. The Kohn–Sham orbitals in the spin-up (spin-down) channel are represented by triangles pointing upwards (downwards). The filled (empty) triangles depict occupied (empty) orbitals. The eux, euy orbitals in the spin-down channel fall into the valence band (VB) and are smeared, so their position is very schematic. However, the eux, euy orbitals in the spin-up channel form resonant and localized states above the VB edge far from the conduction band (CB). We show the optical excitation path of the |3A2g〉 ground state by an inclined arrow pointing upwards. b Visualization of single-particle Kohn–Sham wavefunctions. The gray ball depicts the impurity atom, while the black balls depict the six first neighbor carbon atoms
