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New article by grad student Daniel Wines & Dr. Ataca in JCP

“A pathway toward high-throughput quantum Monte Carlo simulations for alloys: A case study of two-dimensional (2D) GaSxSe1−x”

Daniel Wines, Kayahan Saritas, Can Ataca

STEAM Lab members Daniel Wines and Dr. Ataca and collaborator Dr. Kayahan Saritas (Yale University Applied Physics) developed a high-throughput procedure to use the Diffusion Monte Carlo method to study two-dimensional alloys, using GaSxSe1-x as a case study.

J. Chem. Phys. 155, 194112 (2021); https://doi.org/10.1063/5.0070423

URL: https://aip.scitation.org/doi/full/10.1063/5.0070423

Abstract: The study of alloys using computational methods has been a difficult task due to the usually unknown stoichiometry and local atomic ordering of the different structures experimentally. In order to combat this, first-principles methods have been coupled with statistical methods such as the cluster expansion formalism in order to construct the energy hull diagram, which helps to determine if an alloyed structure can exist in nature. Traditionally, density functional theory (DFT) has been used in such workflows. In this paper, we propose to use chemically accurate many-body variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC) methods to construct the energy hull diagram of an alloy system due to the fact that such methods have a weaker dependence on the starting wavefunction and density functional, scale similarly to DFT with the number of electrons, and have had demonstrated success for a variety of materials. To carry out these simulations in a high-throughput manner, we propose a method called Jastrow sharing, which involves recycling the optimized Jastrow parameters between alloys with different stoichiometries. We show that this eliminates the need for extra VMC Jastrow optimization calculations and results in significant computational cost savings (on average 1/4 savings of total computational time). Since it is a novel post-transition metal chalcogenide alloy series that has been synthesized in its few-layer form, we used monolayer GaSxSe1−x as a case study for our workflow. By extensively testing our Jastrow sharing procedure for monolayer GaSxSe1−x and quantifying the cost savings, we demonstrate how a pathway toward chemically accurate high-throughput simulations of alloys can be achieved using many-body VMC and DMC methods.

Posted: November 18, 2021, 12:14 PM