addition of an extra electron to [$\mathrm{SiVN}^-$]{}, producing [$\mathrm{SiVN}^{2-}$]{}, breaks a [$\mathrm{C}-\mathrm{N}$]{} bond with the nitrogen forming a [$\mathrm{N_{s}}$]{}structure bonded to the Si and two carbons. This geometric distortion to [$\mathrm{SiVN}$]{}results in the lowering of a band gap state which is now accesible for excitation. Examining the orbital characteristics depicted by spin density isosurfaces from DFT, we observe the [$\mathrm{N_{s}^{0}}$]{}-like \[Fig \[fig:orbitals\](c)\] configuration adopted by [$\mathrm{SiVN}^{2-}$]{} \[Fig \[fig:orbitals\](d)\], rather than retaining the configuration of the same band gap state in [$\mathrm{SiVN}^0$]{} \[Fig \[fig:orbitals\](e)\]. Calculations of the [$\mathrm{SiVN}$]{}charge stabilities \[Table \[tab:SiNV\_binding\_energies\]\] indicate that all three charge states are stable, and of these [$\mathrm{SiVN}^-$]{}is least likely to dissociate.

  Defect                                                                                    
  -------------------------- -- ------------------------- --- -------------------------- -- --
  [$\mathrm{SiVN}^0$]{}            [$\mathrm{SiV}^{-}$]{}  +  [$\mathrm{N_{s}^{+}}$]{}      
  [$\mathrm{SiVN}^-$]{}            [$\mathrm{SiV}^{-}$]{}  +  [$\mathrm{N_{s}^{0}}$]{}      
  [$\mathrm{SiVN}^{2-}$]{}        [$\mathrm{SiV}^{2-}$]{}  +  [$\mathrm{N_{s}^{0}}$]{}      

  : Binding energies ($E_\mathrm{bind}$) for each modeled defect through charge-conserving reactions. Displayed errors result from comparing values calculated using LDA and GGA functional.

\[tab:SiNV\_binding\_energies\]

We expect all charge states of the [$\mathrm{SiVN}$]{}to be difficult to identify in IR absorption measurements. The mass of the elements involved, combined with the vacancy, suggests that defect vibrations will be below the lattice cutoff and therefore will contribute to the one-phonon absorption, rather than exhibiting sharp local vibrational 