Crystal Structure Prediction of Binary Alloys via Deep Potential

Abstract

Predicting crystal structure has been a challenging problem in physics and materials science for a long time. A reliable energy calculation engine combined with an efficient global search algorithm, such as particle swarm optimization algorithm or genetic algorithm, is needed to conduct crystal structure prediction. In recent years, machine learning-based interatomic potential energy surface models have been proposed, potentially allowing us to perform crystal structure prediction for systems with the accuracy of density functional theory (DFT) and the speed of empirical force fields. In this paper, we employ a previously developed Deep Potential model to predict the intermetallic compound of the aluminum–magnesium system, and find six meta-stable phases with negative or nearly zero formation energy. In particular, Mg12Al8 shows excellent ductility and Mg5Al27 has a high Young's modulus. Based on our benchmark results, we propose a relatively robust structure screening criterion that selects potentially stable structures from the Deep Potential-based convex hull and performs DFT refinement. By using this criterion, the computational cost needed to construct the convex hull with ab initio accuracy can be dramatically reduced.

High-Throughput Computational Screening for Bipolar Magnetic Semiconductors

“…(3) S filter: for stability of a compound, two important factors are considered here, including formation energy (E f ) and the energy above convex hull (E abh ). The formation energy [29] of a compound is the energy required to produce the system from the most stable crystal structures of the individual components, which is defined as…”

“…A zero E abh indicates that this is the most stable material at its composition [29,30]. Generally speaking, those compounds with negative E f are easy to be synthesized.…”

High-throughput computational screening for bipolar magnetic semiconductors

“…For stability of a compound, two important factors are considered here, including formation energy (E f ) and the energy above convex hull (E abh ). The formation energy 29 of an compound is the energy required to produce the system from the most stable crystal structures of the individual components, which is defined as…”

“…A zero E abh indicates that this is the most stable material at its composition. 29,30 Generally speaking, those compounds with negative E f are easy to be synthesized. However, considering the error of DFT calculations, we use an appropriate standard to select the candidate structures, namely, E f less than 0.01 eV/atom.…”

“…In addition, it is generally believed that structures with E abh less than 0.1 eV/atom can be synthesized experimentally. 29,30 In short, the standard for S filter is {E f ≤ 0.01 eV/atom , E abh ≤ 0.1 eV/atom}. (4) G filter.…”