Al7CX (X = Li-Cs) clusters: Stability and the prospect for cluster materials

Al7C clusters, recently found to have a high-electron affinity and exceptio nal stability, are shown to form ionic molecules when combined with alkali- metal atoms. Our studies, based on an ab initio gradient-corrected density- functional scheme, show that Al7CX (X=Li-Cs) clusters have a very low-elect ron affinity and a high-ionization potential. When combined, the two- and f our-atom composite clusters of Al7CLi units leave the Al7C clusters almost intact. Preliminary studies indicate that Al7CLi may be suitable to form cl uster-based materials.