Structure and bonding of small stoichiometric lithium oxide clusters.

Abstract

Ground-state properties of stoichiometric lithium oxide clusters ${\mathrm{Li}}_{2\mathit{n}}$${\mathrm{O}}_{\mathit{n}}$ (n\ensuremath{\le}6) are studied by means of ab initio molecular-dynamics simulations, in conjunction with a global optimization strategy. For each n value, several stable isomers are found, presenting a remarkable variety of bonding configurations. We analyze the atomic structure, the local coordination, the bond lengths, and the relative stability of these clusters. By defining a mean bond length --- averaged over all atoms having the same coordination number --- we show that it is possible to characterize the global bonding properties of a ${\mathrm{Li}}_{2\mathit{n}}$${\mathrm{O}}_{\mathit{n}}$ cluster at given n despite the structural differences among the various isomers. For some of them, energy barriers can be easily overpassed, making possible a dynamical equilibrium among a few configurations in a temperature range of some hundred K above room temperature. \textcopyright{} 1996 The American Physical Society.