Real-space density-functional calculations for Si divacancies with large size supercell models

First-principles density-functional calculations of divacancies in crystalline silicon are performed with large size super-cell models which correspond to the unit cell of 64-1000 Si atoms. The calculations are performed by the newly developed real-space finite-difference pseudopotential code in parallel computation. It is found that the model size is large enough to provide a converged divacancy structures. A structure which is predicted by the early experiment and the recent cluster model calculation, is not found. Our own cluster calculation also corroborate the finding. (c) 2005 Elsevier B.V. All rights reserved.