  We study the antiferromagnetic phase of the C60-polymer doped with one
electron per one C60 by using a tight-binding model with long-range Coulomb
interactions. The model is solved by the unrestricted Hartree-Fock
approximation, and a phase diagram is obtained by changing Coulomb interaction
strengths and a conjugation parameter between C60 molecules. We find that the
antiferromagnetism is well described by the present model. The comparison with
the photoemission studies shows that the new band around the Fermi energy of
the A1C60 phase can be explaind by the extremely large intrusion of an energy
level into the gap of the neutral system. This indicates that the interaction
effects among electrons are important in doped C60-polymers.
