Ab-initio study of Na n F n and Na n F n?1 clusters: atypical structures

Alkali halide clusters Na _n F _n have most frequently cuboid structures and Na _n F _n?1 clusters are derived from Na _n F _n by removing a F^? centre. An excess electron localises on the site of the removed F^? ion. In this paper, other kind of clusters are studied at the SCF level: i) The non-cubic structures. ii) The cubic Na _n F _n?1 for which the excess electron has no defined site. Due to very large size of these species (at least 27 atoms!) some equivalent fictive linear and planar geometries are studied.