We present a systematic theoretical study about In_n clusters with n=1-10. We explore the lowest-energy structures and investigate their geometric and electronic properties including electronic affinity (EA), ionization potential (IP), HOMO-LUMO gap, second difference of cluster total energy (∆₂E) and spin density (SD) using the DFT method with the B3LYP and M06 functionals, and LANL2DZ.

As a measure of the complexs relative stability, we calculate the binding  energy per atom (E_b) and we observe that increases together with the size of the cluster (up to n=7) and then remains constant at 1,27 eV/atom. Besides, the same lowest-energy structures are obtained with B3LYP and M06, except for In₃ and In₅.

The analysis of EA and IP is reliable with previous DFT results for other metals and calculations using B3LYP present better results according to the bibliography. The HOMO-LUMO gap exhibit odd-even oscillations. For both functionals are observed similar behaviors up to n=6, but do not correlate with the electron-pairing effect according to previous works. For n>6, with M06, maximums in even-clusters are obtained, indicating a more consistent result. Regardless the functional chosen, the ∆₂E it’s higher for In₃ and In₈, indicating that this clusters are most stables than their neighbors. Finally the SD is strongly dependent on the shape and size of the cluster: small changes in the structure cause large changes in the SD and when the number of atoms increases, the reactivity decreases because the spin is scattered over a larger surface.