"No-Pair Bonding" in high-spin lithium clusters: Li-n+1(n) (n=2-6)

High-spin lithium clusters (Li-n+1(n), n = 2-6) have been studied using sev eral density functional methods. Although these high-spin clusters have no bonding electron pairs, they are stable with respect to isolated lithium at oms. Full geometry optimizations have been performed with alternatives unde r a variety of symmetry constraints which led to local minima. In general, the most stable structure is the one with the maximum coordination number f or the lithium atoms. The agreement between B3P86/cc-pVDZ and B3PW91/cc-pVD Z density functional methods with UQCISD(T)/6-31G* and UCCSD(T)/cc-pVDZ cal culations is excellent. Trends of bond dissociation energies are discussed as a function of total number of "bonds" and number of atoms.