modes. Unfortunately, the one-phonon IR absorption of samples D–G contain other unidentified contributions thus no spectrum can be associated with any charge state of [$\mathrm{SiVN}$]{}at the present time.

![a) Schematic of the [$\mathrm{SiVN}$]{}$^{0/-}$ defect, highlighting the defect’s mirror plane. b) Calculated formation energies at varying chemical potentials, $\mu_e$, for [$\mathrm{SiV}$]{}and [$\mathrm{SiVN}$]{}with reference to the intrinsic diamond valence band maximum. Transition levels include charge density offset and Madelung corrections. The calculated conduction band minimum was at . c–e) Electron density on bandgap states for c) the donor state in [$\mathrm{N_{s}^{0}}$]{}; d) the state with an unpaired electron for [$\mathrm{SiVN}^{2-}$]{}; e) the same state for [$\mathrm{SiVN}^0$]{}. Comparison of d) and e) highlights the additional electron in an N-C antibonding orbital in [$\mathrm{SiVN}^{2-}$]{}. Isosurfaces depict a surface of constant spin density: a common spin density threshold was chosen for d) and e) to allow comparison in the same structure; a higher threshold was chosen for c) due to the highly localized nature of the [$\mathrm{N_{s}^{0}}$]{} donor state.[]{data-label="fig:orbitals"}](graphs_combined_wavefunctions_with_charge){width="\columnwidth"}

Defect production
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The addition of silicon (typically via silane) during CVD growth of diamond yields a grown-in (native) population of SiV centers [@Itoh2014; @Rogers2014b]. In an analagous situation to nitrogen, where substitutional nitrogen concentrations are 