Theoretical investigation of geometry and stability of small lithium-iodide Li<inf>n</inf>I (n = 2-6) clusters

Abstract

We present theoretical investigation of the structural characteristics and stabilities of neutral and positively charged LinI (n = 2-6) species. The structural isomers were found by using a randomized algorithm to search for minima structures, followed by B3LYP optimizations; the single-point RCCSD(T)/cc-pwCVTZ(-PP) calculations were performed in order to compute relative energies, binding energies per atom, adiabatic and vertical ionization energies, and dissociation energies. Stability was compared to the pure lithium clusters; there is a typical odd-even alternation; iodine doped clusters are more stable than pure lithium clusters. Lithium "cage" transfers its valence electron to the iodine atom to form neutral I - Lin+ and cationic I - Lin2+ clusters. An electron departures the lithium cage upon ionization. An important reason for the larger stability of closed-shell species is the existence of the HOMO 3c/2e natural bond orbitals. © 2013 Wiley Periodicals, Inc.