Accelerated Prediction of Temperature-Dependent Lattice Thermal Conductivity via Ensembled Machine Learning Models

TL;DR

This paper introduces an ensembled machine learning model that predicts lattice thermal conductivity with near ab initio accuracy across a wide temperature range, enabling rapid screening of thermoelectric materials.

Contribution

The study develops a machine learning approach using ensemble models trained on DFT data, achieving high accuracy and generalization for predicting $ppa_L$ in diverse compounds.

Findings

Achieved an R^2 of 0.9994 and RMSE of 0.0466 W/mK on log-scaled ppa_L.

Successfully predicted ppa_L for unseen compounds with R^2 of 0.961.

Demonstrated high-throughput screening of thermoelectric candidates from large compound databases.

Abstract

Lattice thermal conductivity ($\kappa_L$) is a key physical property governing heat transport in solids, with direct relevance to thermoelectrics, thermal barrier coatings, and heat management applications. However, while experimental determination of $\kappa_L$ is challenging, its theoretical calculation via ab initio methods particularly using density functional theory (DFT) is computationally intensive, often more demanding than electronic transport calculations by an order of magnitude. In this work, we present a machine learning (ML) approach to predict $\kappa_L$ with DFT-level accuracy over a wide temperature range (100-1000 K). Among various models trained on DFT-calculated data obtained from literature, the Extra Trees Regressor (ETR) yielded the best performance on log-scaled $\kappa_L$, achieving an average $R^2$ of 0.9994 and a root mean square error (RMSE) of 0.0466 $W\,m^{-1}\,K^{-1}$. The ETR model also generalized well to twelve previously unseen (randomly chosen) low and high $\kappa_L$ compounds with diverse space group symmetries, reaching an $R^2$ of 0.961 against DFT benchmarks. Notably, the model excels in predicting $\kappa_L$ for both low- and high-symmetry compounds, enabling efficient high-throughput screening. We also demonstrate this capability by screening ultralow and ultrahigh $\kappa_L$ candidates among 960 half-Heusler compounds and 60,000 ICSD compounds from the AFLOW database. This result shows reliability of model developed for screening of potential thermoelectric materials. At the end, we have tested model's prediction ability on systems that have experimental $\kappa_L$ available that shows model's ability to search material that has desirable experimental $\kappa_L$ for thermoelectric applications.