Locality Error Free Effective Core Potentials for 3d Transition Metal Elements Developed for the Diffusion Monte Carlo Method*

Locality errors associated with semilocal pseudopotentials have hampered the application of the diffusion Monte Carlo (DMC) method to transition metal oxides and related compounds. In response, we developed locality error free effective core potentials (named OPH23) based on the pseudoHamiltonian framework for 3d transition metal elements from Cr to Zn. Our carefully optimized OPH23 potentials exhibit transferability errors comparable to ccECP, the state-of-the-art semilocal pseudopotential for DMC, at the quantum chemistry level. Due to the lack of locality errors, OPH23 should exceed semilocal pseudopotentials in accuracy with DMC. 

In our presentation, we will explain the theory behind our OPH23 potentials and discuss the transferability errors. The accompanying manuscript has been approved for publication in The Journal of Chemical Physics and is available on arXiv (https://arxiv.org/abs/2310.08238).