2012/09/30 by Massimo Boninsegni, Saverio Moroni
Physics and Astronomy · #cond-mat.stat-mech #cond-mat.other
paper · pdf · doi:10.1103/physreve.86.056712
published as Phys. Rev. E 86, 056712 (2012) · Seven pages, four figures
arxiv created 2012/11/29 · arxiv updated 2012/11/30
The size of the population of random walkers required to obtain converged estimates in DMC increases dramatically with system size. We illustrate this by comparing ground state energies of small clusters of parahydrogen (up to 48 molecules) computed by Diffusion Monte Carlo (DMC) and Path Integral Ground State (PIGS) techniques. We contend that the bias associated to a finite population of walkers is the most likely cause of quantitative numerical discrepancies between PIGS and DMC energy estimates reported in the literature, for this few-body Bose system. We discuss the viability of DMC as a general-purpose ground state technique, and argue that PIGS, and even finite temperature methods, enjoy more favorable scaling, and are therefore a superior option for systems of large size.