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. 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