We have analyzed the band energy of the t1u, band of A3C60, using the three-molecular-orbital tight-binding model. It turns out that this energy can with a good accuracy be described by the antiferromagnetic Ising model, where the two allowed orientations of each molecule play the role of the two spin directions. We also show that such a description is limited to disordered and short-range ordered structures, while the long-range ordered structures are affected by the band-structure effects leading to peaks in the density of states.
 

Solid State Communications, 91 497-500, 1994.