Does Lanthanum Move Inside Fullerene Cages?

A brief account is given of recent density-functional-based molecular dynamics studies of metallofullerenes with encaged lanthanum. These calculations give the energetically preferred structures of the metal atom inside the cage, thus correcting predictions given so far in the literature, and provide us with detailed information about its motion. An interesting difference is found between the dynamical behavior of the encapsulated atoms in C(60) and in C(82). Our picture is consistent with the available experimental data on La@C(82) and Y@C(82).