Structure and Electronic Properties of Neutral and Negatively Charged RhB_n Clusters (n = 3-10): A Density Functional...

The geometrical structure and electronic properties of the neutral RhB_n and singly negatively charged RhB_n^- clusters are obtained in the range of 3 ≤ n ≤ 10 using the unbiased CALYPSO structure search method and density functional theory (DFT). A combination of the PBE0 functional and the def2-TZVP basis set is used for determining global minima on potential energy surfaces of the Rh-doped B_n clusters. The photoelectron spectra of the anions are simulated using the time-dependent density functional theory (TD-DFT) method. Good agreement between our simulated and experimentally obtained photoelectron spectra for RhB₉^- provides support to the validity of our theoretical method. The relative stabilities of the ground-state RhB_n and RhB_n^- clusters are estimated using the calculated binding energies, second-order total energy differences, and HOMO-LUMO gaps. It is found that RhB₇ and RhB₈^- are the most stable species in the neutral and anionic series, respectively. The chemical bonding analysis reveals that the RhB₈^-cluster possesses two sets of delocalized σ and π bonds. In both cases, the Hückel 4N + 2 rule is fulfilled and this cluster possesses both σ and π aromaticities.