  We study the electronic spectrum for doped electronic states in the
orientationally disordered M3C60 fullerides. Momentum-resolved Green's
functions are calculated within a cluster-Bethe-lattice model, and compared
with results from calculations on periodically repeated supercells containing
quenched orientational disorder. Despite the relatively strong scattering from
orientational fluctuations, the electronic states near the Fermi energy are
well described by propagating states characterized by an effective Bloch wave
vector, and a mean free path of approximately 20 Angstroms. The effective Fermi
surface is calculated in this model. This differs from that previously
calculated for the orientationally ordered crystal, but is relatively well
described within a disorder-averaged virtual-crystal Hamiltonian, which we
derive.
