A first-principles study on the structural and electronic properties of ZnO clusters

Abstract

This work presents a first-principles study of the structural, energetic, and electronic properties of (ZnO)n clusters with n =1 ÷ 10. Various low-energy isomers were constructed and fully optimized using density functional theory within the DMol3 framework with the GGA–PBE functional. The most stable geometries were identified based on total energy calculations. The results reveal a clear size-dependent structural evolution: small clusters (n ≤ 7) favor planar or ring-like geometries, while larger clusters (n ≥ 8) adopt compact three-dimensional configurations with higher symmetry. The calculated average binding energy increases with cluster size, indicating enhanced stability and a tendency for cluster growth. Electronic structure analysis shows that the valence band is mainly contributed by O-2p states, whereas the conduction band is primarily derived from Zn orbitals, confirming the semiconducting nature of the clusters. Charge density difference analysis indicates electron transfer from Zn to O atoms, suggesting strong Zn–O bonding with significant covalent character in these clusters.