Secondly, in contrast to E f prediction, interatomic bond distances played a more substantial role in predicting E g , which may be attributed to the fact that bond distances reflect orbital hybridization and charge transfer. Research on the electronic structure of perovskite materials suggests that electronic states just below the Fermi level and in the conduction bands mostly arise from the hybridization of B and X states, which strongly correlate with the bandgap of perovskite materials. B and X atoms in BX 6 octahedra have smaller atomic radii and shorter bond distances, reflecting stronger orbital hybridization. Additionally, we found that the topmost commonly selected atom features in the four CML models are electron affinity and valence electrons, which are correlated with charge transfer. Given the importance of interatomic bond distances in determining E g , it is imperative to incorporate bond features as inputs for ML training to improve E g prediction accuracy.