Structural evolution and stabilities of (CuIn) _<i>n</i> Te ₂ and ((CuIn) _<i>n</i> Te ₂ ) ⁻ ( <i>n</i> = 1–8) clusters <i>via</i> DFT study

CuInTe₂ is a promising semiconductor with a tunable bandgap of 1.0-1.2 eV, enabling it to efficiently absorb sunlight and convert it into usable energy. Following this development, characterization of its structural and electronic properties is currently underway. In this study, the Vienna <i>Ab Initio</i> Simulation Package (VASP) with density functional theory (DFT) and plane-wave basis sets was used to investigate the structural and electronic properties of both neutral and anionic clusters. For (CuIn) _<i>n</i> Te₂ and ((CuIn) _<i>n</i> Te₂)^- (<i>n</i> = 1-8) clusters, geometric optimization revealed the lowest-energy isomers, all of which adopt cubic chalcopyrite structures. According to the results, the low-lying energy geometry of Cu₂In₂Te₂ and (CuInTe₂)^- clusters exhibit their maximum relative stability. The (CuIn) _<i>n</i> Te₂ thin-film experimental finding of 1.85 eV is a good match with their mean HOMO-LUMO gaps of 1.652 eV and 2.464 eV. Binding energy per atom increases with cluster size, although the HOMO-LUMO gap breaks at <i>n</i> = 5, most likely as a result of bond-specific interactions and orbital hybridization. The Cu₂In₂Te₂ cluster stands out with maximum HOMO-LUMO gap and dissociation energy, consistent with its enhanced stability. Adiabatic ionization potentials decrease with cluster size, indicating growing metallic character, while dissociation energies show odd-even oscillations but overall increase as size grows. Partial charge density analysis shows that both neutral and anion clusters are significant for semiconductor applications, including photovoltaic cells and related devices.