Nonlocal pseudopotentials and time-step errors in diffusion Monte Carlo

Abstract

We present a version of the T-moves approach for treating nonlocal pseudopotentials in diffusion Monte Carlo which has much smaller time-step errors than the existing T-moves approaches, while at the same time preserving desirable features such as the upper-bound property for the energy. In addition, we modify the reweighting factor of the projector used in diffusion Monte Carlo to reduce the time-step error. The latter is applicable not only to pseudopotential calculations but to all-electron calculations as well.

25 pages, 4 figures; additional figures added, expanded discussion of results, added VMC energies to suppl.pdf; We discovered a programming error which had led us to recommend a reweighting factor which gives a suboptimal time-step error. The reweighting factor in Eq. 9 has been replaced with a better recommendation, and the results have been updated. The conclusions of the paper are unchanged