Quantum-Accurate Spectral Neighbor Analysis Potential Models for Ni-Mo Binary Alloys and FCC Metals

TL;DR

This paper develops a machine learning-based spectral neighbor analysis potential (SNAP) model for Ni-Mo alloys and FCC metals, achieving near-DFT accuracy and outperforming traditional potentials in predicting phase diagrams and material properties.

Contribution

The paper extends the SNAP model to bcc-fcc binary alloys, demonstrating improved accuracy over existing potentials and providing a systematic development process for multicomponent alloy models.

Findings

SNAP models outperform EAM and MEAM potentials in accuracy.

The Ni-Mo SNAP model accurately predicts phase diagrams and material properties.

The approach enables large-scale, long-time simulations of alloy systems.

Abstract

In recent years, efficient inter-atomic potentials approaching the accuracy of density functional theory (DFT) calculations have been developed using rigorous atomic descriptors satisfying strict invariances, for example, to translation, rotation, permutation of homonuclear atoms, among others. In this work, we generalize the spectral neighbor analysis potential (SNAP) model to bcc-fcc binary alloy systems. We demonstrate that machine-learned SNAP models can yield significant improvements even over well-established, high-performing embedded atom method (EAM) and modified EAM (MEAM) potentials for fcc Cu and Ni. We also report on the development of a SNAP model for the fcc Ni-bcc Mo binary system by machine learning a carefully-constructed large computed data set of elemental and intermetallic compounds. We demonstrate that this binary Ni-Mo SNAP model can achieve excellent agreement with experiments in the prediction of Ni-Mo phase diagram as well as near-DFT accuracy in the prediction of many key properties such as elastic constants, formation energies, melting points, etc., across the entire binary composition range. In contrast, the existing Ni-Mo EAM has significant errors in the prediction of the phase diagram and completely fails in binary compounds. This work provides a systematic model development process for multicomponent alloy systems, including an efficient procedure to optimize the hyper-parameters in the model fitting, and paves the way to long-time, large-scale simulations of such systems.