Abstract
First-principles methods are used to investigate the self-interstitial and its aggregates in diamond. The experimental assignment of the spin-1 EPR center to the single interstitial has been questioned because of the small fine-structure term observed. We calculate the spin-spin interaction tensor for the three interstitial defects and and compare with the experimental D tensors. The results give support for the assignments of the single and di-interstitials to microscopic models and allow us to conclusively identify a recently observed EPR center, with This identification, in turn, suggests a low-energy structure for and a generic model for an extended defect called the platelet. We also determine the optical properties of as well as its piezospectroscopic or stress tensor and find these to be in agreement with experiment. Several multi-interstitial defects are found to possess different structural forms which may coexist. We propose that a different form of the charged defect gives rise to the optical peak. Several structures of the platelet are considered, and we find that the lowest-energy model is consistent with microscopic and infrared studies.
- Received 26 September 2000
DOI:https://doi.org/10.1103/PhysRevB.63.195208
©2001 American Physical Society