Using atom superposition and electron delocalization MO method (ASED-MO), the authors have investigated the formation of MC60 with an alkali metal atom M added inside or outside the footballene. The stability, electronic structure and distribution of electron charge have been discussed. It is pointed out that the equilibrium position of Li atom in LiC60 is apart from the center of the footballene while the other alkali atoms, Na, K, Rb and Cs all locate just at the center of the corresponding MC60 mols.; atom Rb and Cs being outside the footballene are more stable than being inside. A further discussion concludes that according to the radii of the metal atoms and footballene spherical radius, one may predict what atoms can stably exist inside the footballene.

Key words: SODIUM COMPOUNDS, POTASSIUM COMPOUNDS, LITHIUM COMPOUNDS, CESIUM COMPOUNDS, ELECTRONIC STRUCTURE, MOLECULAR ORBITAL THEORY, RUBIDIUM COMPOUNDS, ALKALI METAL COMPOUNDS, FULLERENES, FULLERENES