Prospects and Scaling Properties of Quantum Monte Carlo Forces for Heavier Ions

Quantum Monte Carlo (QMC) forces are an important quantity for structural relaxation, force-field generation and studying, for instance, phonon interactions. However, they face well-known challenges due to difficult statistics [1] and Pulay corrections [2]. Powerful techniques exist to mitigate these problems, but the prospects of QMC forces in state-of-the-art applications remain somewhat uncharted. Here we give an outlook of continuum variational Monte Carlo and diffusion Monte Carlo forces in applications including heavier than usual elements, such as third row transition metals which require the use of pseudopotentials. We conclude by reporting the scaling properties of systematic errors and intrinsic variances of forces with the effective pseudopotential valence charge [3].

[1] P.L. Rios, G.J. Conduit, Phys. Rev. E 99, 063312, 2019
[2] R. Assaraf, M. Caffarel, J. Chem. Phys. 119, 10536, 2003
[3] J. Tiihonen, R.C. Clay III, J.T. Krogel, 2020, submitted