Nonlocal pseudopotentials and time-step errors in diffusion Monte Carlo

TL;DR

This paper introduces an improved T-moves method for diffusion Monte Carlo that significantly reduces time-step errors while maintaining energy bounds, and also proposes a modification to the reweighting factor applicable to various calculations.

Contribution

The authors develop a new T-moves approach with smaller time-step errors and modify the reweighting factor to enhance accuracy in diffusion Monte Carlo simulations.

Findings

Reduced time-step errors compared to previous T-moves methods.

Preservation of the upper-bound property for energy calculations.

Applicable to both pseudopotential and all-electron calculations.

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.