Oxygen and vacancy defects in silicon. A quantum mechanical characterization through the IR and Raman spectra.

The Infrared (IR) and Raman spectra of various defects in silicon, containing both oxygen atoms (in the interstitial position, O) and a vacancy, are computed at the quantum mechanical level by using a periodic supercell approach based on a hybrid functional (B3LYP), an all-electron Gaussian-type basis set, and the Crystal code. The first of these defects is VO: the oxygen atom, twofold coordinated, saturates the unpaired electrons of two of the four carbon atoms on first neighbors of the vacancy. The two remaining unpaired electrons on the first neighbors of the vacancy can combine to give a triplet (S = 1) or a singlet (S = 0) state; both states are investigated for the neutral form of the defect, together with the doublet solution, the ground state of the negatively charged defect.

Interstitial defects in diamond: A quantum mechanical simulation of their EPR constants and vibrational spectra.

The local geometry, electronic structure, and vibrational features of three vicinal double interstitial defects in diamond, II, II, and II, are investigated and compared with those of three "simple" ⟨100⟩ interstitial defects, I, I, and I, previously reported by Salustro et al. [Phys. Chem.