Electronic structure calculations by quantum Monte Carlo methods

Recent development of quantum Monte Carlo (QMC) methods and their applications will be presented. The methodology of construction of many-body correlated wave functions will be briefly described together with the variational and diffusion Monte Carlo methods. Several applications of QMC such as energy ordering for Si and C cluster isomers and cohesive energies and excitations in insulating solids will be mentioned. Overall, the QMC methods are currently applicable to a few hundred valence electron sp systems with statistical uncertainties of the order of 0.1 eV for energy differences and decrease errors of mean-field methods by a factor of 5-10 when compared with available experiments. Comparisons with other explictly correlated methods indicate the QMC advantages in the efficient description of correlation effects and scaling in the number of electrons. The variety of treated systems demonstrates the usefulness and wide applicability of this approach. These advantages together with the obtained results show that QMC is becoming a powerful predictive tool and a new alternative for ab initio electronic structure calculations.