Within first-principles density functional theory, we explore the feasibility of using
metallofullerenes as efficient hydrogen storage media. In particular, we systematically investigate the
interaction between hydrogen molecules and La encapsulated all-carbon fullerenes, Cn (20≤n≤82),
focusing on the role of transferred charges between the metal atoms and fullerenes on the affinity of
hydrogen molecules to the metallofullerenes. Our calculations show that three electrons are transferred
from La atom to fullerene cages, while the induced charges are mostly screened by the fullerene cages.
We find the local enhancement of molecular hydrogen affinity to the fullerenes to be sensitively
dependent on the local bonding properties, rather than on the global charging effects.