Ab initio simulations of non-stoichiometric lithium[ndash ]oxygen clusters

Abstract

Bonding and electronic properties of non-stoichiometric lithium oxide clusters Li_nO₂ (n⩽10) are studied by means of abinitio simulations. We focus on the first stage of lithium enrichment of stoichiometric Li₄O₂, where the formation of additional Li–O bonds is favoured. The bonding configuration of the lowest-energy isomers and their stability are analysed in detail, and their structures compared to those found in bulk non-stoichiometric alkali-metal suboxides. As a function of the increasing number of excess Li atoms, coexistence of an ionic and a delocalized character of the electronic density takes place, accompanied by a progressive Li–O bond weakening. These issues, and the existence of odd–even staggering of electronic properties, are discussed, in relation to recent experiments and other anion-deficient systems such as defective oxide surfaces and alkali-metal halide clusters.