Electronic Stability and Global Reactivity Descriptors of Cu–Sc Nanoclusters: A Multilevel DFT–PCA Study

The electronic stability and global reactivity of CuxScγ (x + y = 4) bimetallic nanoclusters were investigated within the framework of rational design of functional materials and active catalytic phases. M06-2X/def2-TZVP DFT was used for geometric optimization and electronic characterization, and global descriptors were calculated, including ΔEgap, chemical toughness, chemical potential, and electrophilicity. The orbital contribution was analyzed using DOS/PDOS with Multiwfn; PCA and ANOVA were applied to quantify descriptor–structure relationships. The results show that adding Sc changes the cluster’s electron density and stiffness in a consistent manner, enabling distinction between more stable and more reactive configurations. In particular, Cu3Sc is the most electronically stable, exhibiting the highest ΔEgap, while Cu2Sc2 shows a more tunable electronic response, consistent with scenarios requiring greater reactivity. Multivariate analysis shows that ΔEgap accounts for most of the electronic variability in the dataset, making it the primary descriptor for selection and design. Taken together, these results open a descriptor-guided path to designing active Cu–Sc phases for supported catalysis and to their assembly into tunable metal nanocomposites.