Extending the Accuracy of the SNAP Interatomic Potential Form

TL;DR

This paper introduces a quadratic extension to the SNAP interatomic potential, significantly improving accuracy with minimal additional computational cost, demonstrated on tantalum structures.

Contribution

It proposes a quadratic form of the SNAP potential, enhancing accuracy over the linear version while maintaining computational efficiency.

Findings

Quadratic SNAP outperforms linear SNAP in accuracy.

The new form is computationally efficient.

Effective for modeling tantalum structures.

Abstract

The Spectral Neighbor Analysis Potential (SNAP) is a classical interatomic potential that expresses the energy of each atom as a linear function of selected bispectrum components of the neighbor atoms. An extension of the SNAP form is proposed that includes quadratic terms in the bispectrum components. The extension is shown to provide a large increase in accuracy relative to the linear form, while incurring only a modest increase in computational cost. The mathematical structure of the quadratic SNAP form is similar to the embedded atom method (EAM), with the SNAP bispectrum components serving as counterparts to the two-body density functions in EAM. The effectiveness of the new form is demonstrated using an extensive set of training data for tantalum structures. Similarly to artificial neural network potentials, the quadratic SNAP form requires substantially more training data in order to prevent overfitting. The quality of this new potential form is measured through a robust cross-validation analysis.