By using the first principles energy band calculations, it is found that the injection of electron alone into C-60, though decreasing the polymerization energy barrier, increases the instability of the polymeric C-60 chain, and cannot cause a spontaneous polymerization as previously proposed. Inclusion of the electrostatic attraction between the C-60(n-) and counterions, however, can dramatically stabilize the polymeric C-60(n-) chains at n = 1 and 3, accompanied by a further decrease in the polymerization energy barrier, and eventually drives an observable spontaneous polymerization of the C-60(n-) chains in the fcc fullerides at these two doping levels. (C) 2004 Elsevier B.V. All rights reserved.