Electronic Structure and Thermochemical Properties of Small Neutral and Cationic Lithium Clusters and Boron-Doped Lithium Clusters: Lin0/+ and LinB0/+ (n=1-8)

The stability, electronic structure, and thermochemical properties of the pure Li-n and boron-doped LinB (n = 1-8) clusters in both neutral and cationic states are studied using electronic structure methods. The global equilibrium structures are established, and their heats of formation are evaluated using the G3B3 and CCSD(T)/CBS methods based on the density functional theory geometries. Theoretical adiabatic ionization energies (IEa) for the Li-n clusters are in good agreement with experiment: Li-2 (G3B3, 5.21 eV; CCSD(T), 5.14 eV; expt, 5.1127 +/- 0.0003 eV), Li-3 (4.16, 4.11, 4.08 +/- 0.10), Li-4 (4.76, 4.68, 4.70 +/- 0.05), Li-5 (4.11, 4.06, 4.02 +/- 0.10), Li-6 (4.46, 4.32, 4.20 +/- 0.10), Li-7 (4.07, 3.99, 3.94 +/- 0.10), and Li-8 (4.49, 4.31, 4.16 +/- 0.10). The Li-4 experimental IEa has been revised on the basis of the Franck-Condon simulations. Species Li5B, Li6B+, Li7B, and Li8B+ exhibit high stability as compared to their neighbors, which can be understodd by considering the magic numbers of the phenomenological shell model (PSM).