# "One defect, one potential" strategy for accurate machine learning prediction of defect phonons

## TL;DR

This paper introduces a 'one defect, one potential' machine learning approach that achieves DFT-level accuracy in defect phonon calculations while significantly reducing computational costs, enabling large-scale simulations.

## Contribution

The authors develop a defect-specific MLIP training strategy that maintains high accuracy in phonon predictions across supercell sizes, surpassing previous ML approaches.

## Key findings

- Achieves DFT-level phonon accuracy with MLIP
- Reduces computational cost by over an order of magnitude
- Accurately predicts photoluminescence spectra and nonradiative rates

## Abstract

Atomic vibrations play a critical role in phonon-assisted electron transitions at defects in solids. However, accurate phonon calculations in defect systems are often hindered by the high computational cost of large-supercell first-principles calculations. Recently, foundation models, such as universal machine learning interatomic potentials (MLIPs), emerge as a promising alternative for rapid phonon calculations, but the quantitatively low accuracy restricts its fundamental applicability for high-level defect phonon calculations, such as nonradiative carrier capture rates. In this paper, we propose a "one defect, one potential" strategy in which an MLIP is trained on a limited set of perturbed supercells. We demonstrate that this strategy yields phonons with accuracy comparable to density functional theory (DFT), regardless of the supercell size. The predicted accuracy of defect phonons is validated by phonon frequencies, Huang-Rhys factors, and phonon dispersions. Further calculations of photoluminescence (PL) spectra and nonradiative capture rates based on this defect-specific model also show good agreements with DFT results, meanwhile reducing the computational expenses by more than an order of magnitude. Our approach provides a practical pathway for studying defect phonons in 10$^4$-atom large supercell with high accuracy and efficiency.