The relaxed and unrelaxed formation energies of neutral antisites and interstitial defects in InP were calculated using ab initio density functional theory and simple cubic super-cells of up to 512 atoms. The finite-size errors in the formation energies of all the neutral defects arising from the super-cell approximation were examined and corrected for using finite-size scaling methods, which were shown to be a very promising approach to the problem. Elastic errors scale linearly, while the errors arising from charge multipole interactions between the defect and its images in the periodic boundary conditions had a linear plus a higher order term, for which a cubic provides the best fit. These latter errors were shown to be significant even for neutral defects. Instances were also presented where even the 512 atom super-cell was not sufficiently converged. Instead, physically relevant results could be obtained only by finite-size scaling the results of calculations in several super-cells, up to and including the 512 atom cell and in extreme cases possibly even including the 1000 atom super-cell.

Finite-Size Scaling as a Cure for Supercell Approximation Errors in Calculations of Neutral Native Defects in InP. C.W.M.Castleton, S.Mirbt: Physical Review B, 2004, 70[19], 195202 (13pp)