Vibrational and elastic effects of point defects in silicon

We calculate the free energies and normal modes associated with point defects in silicon. The dynamical matrices of a large relaxed supercell of perfect silicon and supercells containing defects are calculated. Diagonalization gives all the vibrational frequencies, and localized defect modes are found from the eigenvectors. The elastic effect of the defects is found by a method involving inversion of the dynamical matrices. The free energy and vibrational entropy of the defects are found by standard statistical techniques. © 1993 The American Physical Society.