Quantum Monte Carlo approaches such as the diffusion Monte Carlo method were among the most accurate many-body methods for extended systems. Their scaling well-suited them for defect calculations in solids. The various approximations needed for diffusion Monte Carlo calculations of solids and the results of previous diffusion Monte Carlo calculations for point defects in solids were reviewed here. Finally, estimates were made of how approximations affected the accuracy of calculations for self-interstitial formation energies in silicon, and diffusion Monte Carlo values of 4.4, 5.1 and 4.7eV were predicted for the X, T and H interstitial defects, respectively, in a 16(+1)-atom super-cell.

Accuracy of Quantum Monte Carlo Methods for Point Defects in Solids. W.D.Parker, J.W.Wilkins, R.G.Hennig: Physica Status Solidi B, 2011, 248[2], 267–74