AB-INITIO STUDY OF STRUCTURAL AND OPTICAL-PROPERTIES OF NONSTOICHIOMETRIC ALKALIMETAL-OXIDES

Structural and optical properties of nonstoichiometric LinO and NanO ( n = 3, 4) clusters containing one and two excess electrons are studied using ab-initio methods accounting for electron correlation. We show that calculated absorption patterns are excellent fingerprints of stru ctural and bonding properties. The optical response of Li4O and Na4O c lusters with the most stable tetrahedral type structures is characteri zed by a common feature, that is the appearance of a dominant intense transition in infrared regime although excess of electrons are not loc alized, as it is the case for small alkali-halide clusters, with cuboi d corner vacancy (surface F-center in finite systems).