Caged-electron states and split-electron states in the endohedral alkali C60

Abstract

The low-lying electronic states of neutral X@C₆₀ (X = Li, Na, K, Rb) have been computed and analyzed by employing state-of-the-art high level many-electron methods. Apart from the common charge-separated states, well known to be present in endohedral fullerenes, one non-charge-separated state has been found in each of the investigated systems. In Li@C₆₀ and Na@C₆₀, the non-charge-separated state is a caged-electron state already discussed before for Li@C₆₀. This indicates that the application of this low-lying state of Li@C₆₀ discussed before is also applicable for Na@C₆₀. In K@C₆₀ and Rb@C₆₀, the electronic radial distribution analysis shows that this hitherto unknown non-charge-separated state possesses a different nature from that of a caged-electron state.