Quantum Monte Carlo study of silicon self-interstitials

An accurate treatment of electron correlation in real materials presents a formidable challenge to condensed matter theorists and quantum chemists. We use the fixed-node diffusion quantum Monte Carlo (DMC) method, which is one of the most accurate methods known for calculating the energies of many-electron systems. The computational cost scales as the cube of the system size, which is much more favourable than other correlated wave function methods, and allows applications to large systems. A basic introduction to the DMC technique is given, and work on self-interstitial defects in silicon is described.