Total-energy ab initio calculations, which were based upon the local density functional, pseudopotential and super-cell approximations were used to investigate C defects in Si. The geometry and formation energies of substitutional and impurity-vacancy defects were studied; including the relaxation of nearest- and next-nearest neighbors. The results for substitutional C appeared to be consistent with a previously suggested reinterpretation of available experimental data on formation energies. The results for the interaction energy between a C atom and a Si vacancy predicted a binding energy of 0.19eV.

Ab initio Investigation of Carbon-Related Defects in Silicon. A.Dal Pino, A.M.Rappe, J.D.Joannopoulos: Physical Review B, 1993, 47[19], 12554-7