Investigation of a Quantum Monte Carlo Protocol To Achieve High Accuracy and High-Throughput Materials Formation Energies

High-throughput calculations
based on density functional theory
(DFT) methods have been widely implemented in the scientific community.
However, depending on both the properties of interest as well as particular
chemical/structural phase space, accuracy even for correct trends
remains a key challenge for DFT. In this work, we evaluate the use
of quantum Monte Carlo (QMC) to calculate material formation energies
in a high-throughput environment. We test the performance of automated
QMC calculations on 21 compounds with high quality reference data
from the Committee on Data for Science and Technology (CODATA) thermodynamic
database. We compare our approach to different DFT methods as well
as different pseudopotentials, showing that errors in QMC calculations
can be progressively improved especially when correct pseudopotentials
are used. We determine a set of accurate pseudopotentials in QMC via
a systematic investigation of multiple available pseudopotential libraries.
We show that using this simple automated recipe, QMC calculations
can outperform DFT calculations over a wide set of materials. Out
of 21 compounds tested, chemical accuracy has been obtained in formation
energies of 11 structures using our QMC recipe, compared to none using
DFT calculations.