  Formation and excitation energies as well charge transition levels, are
determined forthe substitutional nitrogen (Ns),the vacancy (V) and related
point defects (NV, NVH, N2, N2V and V2) by screened non-local hybrid density
functional supercell plane wave calculations in bulk diamond. In additionthe
activation energy for V and NV diffusion is calculated.We find good agreement
between theory and experiment for the previously well-establisheddata, and
predict missing ones. Based on the calculated properties of these defects, the
formation of the negatively charged nitrogen-vacancy center is studied, which
is a prominent candidate for application in quantum information processing and
for nanosensors. We find that the concentration of NV defects are limited in
natural diamonds due to the relatively high formation energy of NV. Our results
imply that NV defects dominantly form just in the early stage of annealing in
N-doped and irradiated diamonds. We find that the amphoteric divacancy defect
with multiple acceptor states may significantly influence the charge state and
photo-stability of NV in irradiated diamond samples.
