Quasi-one-dimensional response of the three-dimensional electronic systems AC₆₀

The stability of the metallic phase for the electronically three-dimensional AC$ 60$ compounds is considered theoretically. A calculation of a possible metal-insulator transition temperature as a function of the degree of imperfect nesting of the Fermi surface is performed. We find that RbC$ 60$ and CsC$ 60$ are unique systems so far where the instability of the metallic phase originates from the nearly half filled conduction band and not from a low dimensionality of the electronic properties.