  Point defects are responsible for a wide range of optoelectronic properties
in materials, making it crucial to engineer their concentrations for novel
materials design. However, considering the plethora of defects in co-doped
semiconducting and dielectric materials and the dependence of defect formation
energies on heat treatment parameters, process design based on an experimental
trial and error approach is not an efficient strategy. This makes it necessary
to explore computational pathways for predicting defect equilibria during heat
treatments. The accumulated experimental knowledge on defect transformations in
diamond is unparalleled. Therefore, diamond is an excellent material for
benchmarking computational approaches. By considering nitrogen, hydrogen, and
silicon doped diamond as a model system, we have investigated the pressure
dependence of defect formation energies and calculated the defect equilibria
during heat treatment of diamond through ab-initio calculations. We have
plotted monolithic-Kr\"oger-Vink diagrams for various defects, representing
defect concentrations based on process parameters, such as temperature and
partial pressure of gases used during heat treatments of diamond. The method
demonstrated predicts the majority of experimental data, such as nitrogen
aggregation path leading towards the formation of the B center, annealing of
the B, H3, N3, and NVHx centers at ultra high temperatures, the thermal
stability of the SiV center, and temperature dependence of NV concentration. We
demonstrate the possibility of designing heat treatments for a wide range of
semiconducting and dielectric materials by using a relatively inexpensive yet
robust first principles approach, significantly accelerating defect engineering
and high-throughput novel materials design.
