A path integral ground state method

Ground state expectation values are obtained by using a path integral ground state Monte Carlo method. The method allows calculations of ground state expectation values without the extrapolations often used with Green's function and diffusion Monte Carlo methods. We compare our results with those of Green's function Monte Carlo by calculating some ground state properties of the van der Waals complex He2Cl2 as well as the infinite systems liquid and solid He-4. Advantages and disadvantages of the present method with respect to previous ones are discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)00328-7].