In the case of the unseen structure mp -5229 (Figure ), COMPGNN-Large still attains less than half the error of GEOCGNN and a significantly smaller variance across different supercell predictions. In contrast, the extension to the reciprocal space features in COMPGNN-Light+k prompted similar performance to GEOGCNN, reducing the stability of predictions across supercell settings. Supplementary Table summarises in detail the prediction results for all supercell configurations.