The nitrogen-vacancy (NV) center in diamond is the prototype quantum defect that enables a variety of diamond-based quantum technologies. However, charge-state instability and spectral diffusion, often induced by substitutional nitrogen impurities (${\mathrm{N}}_{\mathrm{C}}$), remain key challenges for device performance. Here, we employ first-principles density functional theory calculations to quantitatively investigate nonradiative carrier capture processes mediated by multiphonon emission at both the NV center and the ${\mathrm{N}}_{\mathrm{C}}$ impurity. For relevant cases, we also compute the rates of radiative and thermal emission processes. For ${\mathrm{N}}_{\mathrm{C}}^0\to {\mathrm{N}}_{\mathrm{C}}^{-}$, we obtain an electron capture coefficient of $2.2\times {10}^{-8}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 300 K. Both the magnitude and the temperature dependence are in excellent agreement with experimentally measured capture cross sections. Electron capture at ${\mathrm{N}}_{\mathrm{C}}^{+}$ is even faster, with a capture coefficient of $1.0\times {10}^{-4}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 300 K. For the NV center, we find that carrier capture rates involving only the ground states of ${\mathrm{NV}}^0$ and ${\mathrm{NV}}^{-}$ are negligibly slow. However, capture into the excited states (${\mathrm{NV}}^{0*}$ and ${\mathrm{NV}}^{-*}$) is significantly faster. In particular, the capture coefficient for the hole capture process ${\mathrm{NV}}^{-}\to {\mathrm{NV}}^{0*}$ is as large as $1.8\times {10}^{-7}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ and largely temperature independent. Hole capture at ${\mathrm{NV}}^{-}$ will thus occur via nonradiative capture into an excited state of ${\mathrm{NV}}^0$ followed by fast radiative decay to the ${\mathrm{NV}}^0$ ground state. Similarly, electron capture at ${\mathrm{NV}}^0$ will occur via the ${\mathrm{NV}}^0\to {\mathrm{NV}}^{-*}\to {\mathrm{NV}}^{-}$ pathway, but with a lower nonradiative capture coefficient ($2.1\times {10}^{-9}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ at 300 K). Our calculated capture coefficients and rates provide essential information for analyzing charge-state dynamics.

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• Charge dynamics
• Electronic structure
• Nitrogen vacancy centers in diamond
• Quantum information with solid state qubits