Free-energy calculations of intrinsic point defects in silicon

We study the energetics of various point defects in silicon using ab initio density-functional methods. The formation free energies are calculated from the harmonic phonon frequencies, which are determined from ab initio density-functional perturbation theory calculations. We deduce the concentrations of defects as a function of temperature and compare them with experimental estimates. The localized vibrational modes associated with the various defects are described.