Prediction of Frequency-Dependent Optical Spectrum for Solid Materials: A Multi-Output & Multi-Fidelity Machine Learning Approach

TL;DR

This paper introduces a multi-output, multi-fidelity machine learning framework using deep graph neural networks to accurately predict the frequency-dependent optical spectra of solid materials directly from crystal structures, facilitating rapid material screening.

Contribution

It develops novel multi-output and multi-fidelity GNN models for predicting complex optical spectra, addressing data scarcity and extending predictions across a broad frequency range.

Findings

Accurate prediction of dielectric functions across infrared, visible, and ultraviolet spectra.

Effective use of transfer learning and fidelity embedding to mitigate limited high-fidelity data.

Enhanced modeling of solar cell absorption metrics through integrated learning strategies.

Abstract

The frequency-dependent optical spectrum is pivotal for a broad range of applications, from material characterization to optoelectronics and energy harvesting. Data-driven surrogate models, trained on density functional theory (DFT) data, have effectively alleviated the scalability limitations of DFT while preserving its chemical accuracy, expediting material discovery. However, prevailing machine learning (ML) efforts often focus on scalar properties such as the band gap, overlooking the complexities of optical spectra. In this work, we employ deep graph neural networks (GNNs) to predict the frequency-dependent complex-valued dielectric function across the infrared, visible, and ultraviolet spectra directly from crystal structures. We explore multiple architectures for multi-output spectral representation of the dielectric function and utilize various multi-fidelity learning strategies, such as transfer learning and fidelity embedding, to address the challenges associated with the scarcity of high-fidelity DFT data. Additionally, we model key solar cell absorption efficiency metrics, demonstrating that learning these parameters is enhanced when integrated through a learning bias within the learning of the frequency-dependent absorption coefficient. This study demonstrates that leveraging multi-output and multi-fidelity ML techniques enables accurate predictions of optical spectra from crystal structures, providing a versatile tool for rapidly screening materials for optoelectronics, optical sensing, and solar energy applications across an extensive frequency spectrum.