Path Integral Ground State with a Fourth-Order Propagator: Application   to Condensed Helium
  Ground state properties of condensed Helium are calculated using the Path Integral Ground State (PIGS) method. A fourth-order approximation is used as short (imaginary) time propagator. We compare our results with those obtained with other Quantum Monte Carlo techniques and different propagators. For this particular application, we find that the fourth-order propagator performs comparably to the pair product approximation, and is far superior to the primitive approximation. Results obtained for the equation of state of condensed Helium show that PIGS compares favorably to other QMC methods traditionally utilized for this type of calculation. 
Javier E. Cuervo, Pierre-Nicholas Roy and Massimo Boninsegni