Ab initio calculation of endohedral fullerenes with various metal atoms
  The model of endofullerenes M@C60 with M=Li,Na,Cs,Cu,Ag are proposed for study an effect of the nature of endoatoms upon features of the minimum energy structures. They were calculated by SCF Hartree-Fock method with ECP (Ag and Cs) and all-electronic basis sets assuming arbitrary symmetry distortion (C1 point group). All models display the off-center position for the endoatoms and the charge transfer between M and the carbon cage strongly dependent on the nature of endoatoms. Ionization potentials and atomic radii are proposed as the basic factors providing the properties of endofullerenes 
V.S. Gurin