Explainable GNN-Derived Structure-Property Relationships in Interstitial-Alloy Materials

This study presents a novel approach to understanding the structure-property relationships in non-stoichiometric materials and interstitial alloys using Graph Neural Networks (GNNs). Specifically, we apply the Crystal Graph Convolutional Network (CGCNet) to predict the properties of transition-metal carbides, Mo$_2$C and Ti$_2$C, and introduce the Crystal Graph Explainer (CGExplainer) enabling model interpretability. CGCNet outperforms traditional human-derived interatomic potential models (IAPs) in prediction accuracy and data efficiency, with significant improvements in the ability to extrapolate properties to larger supercells. Additionally, the CGExplainer tool enables detailed analysis of the relative spatial positioning of atomic ensembles, revealing key atomic arrangements that govern material properties. This work highlights the potential of GNN-based approaches for rapidly discovering complex structure-property relationships and accelerating the design of materials with customized properties, particularly for alloys with variable atomic compositions. Our methodology offers a robust framework for future materials discovery, extending the applicability of GNNs to a broader range of materials systems.