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

The geometrical structure and electronic properties of the neutral RhBn and singly negatively charged RhBn- 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 PBEO 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 RhBn and RhBn- 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 RhB(8)(-)cluster possesses two sets of delocalized sigma and pi bonds. In both cases, the Hiickel 4N + 2 rule is fulfilled and this cluster possesses both sigma and pi aromaticities.