ELECTRONIC-STRUCTURE CALCULATIONS BY QUANTUM MONTE-CARLO METHODS

Recent development of quantum Monte Carlo (QMC) methods and their appl ications will be presented. The methodology of construction of many-bo dy correlated wave functions will be briefly described together with t he variational and diffusion Monte Carlo methods. Several applications of QMC such as energy ordering for Si and C cluster isomers and cohes ive energies and excitations in insulating solids will be mentioned. O verall, the QMC methods are currently applicable to a few hundred vale nce electron sp systems with statistical uncertainties of the order of 0.1 eV for energy differences and decrease errors of mean-field metho ds by a factor of 5-10 when compared with available experiments. Compa risons with other explictly correlated methods indicate the QMC advant ages in the efficient description of correlation effects and scaling i n the number of electrons. The variety of treated systems demonstrates the usefulness and wide applicability of this approach. These advanta ges together with the obtained results show that QMC is becoming a pow erful predictive tool and a new alternative for ab initio electronic s tructure calculations.