The band structure of a C60 solid was calculated and a tight-binding parametrization of t1u was found ( Phys. Rev. B 46 , 1773 (1992)). This parametrization was extended to the t1g and the hu bands (Phys. Rev. B 51, 17446 (1995)).
The influence of the alkali atoms on the t1u band has been studied. While the influence is small for A3C60 ( Phys. Rev. B 46 , 1773 (1992)), there is a substantial influence for A4C60.
The effects of the deviations from stoichiometry in A(3-x)C60 have been studied in a tight-binding model, using the Hartree approximation ( Recent Advances in the Chemistry and Physics of Fullerenes and related Materials, Vol. 5, Eds. K.M. Kadish and R.S. Ruoff, Electrochemistry Society Proceedings 97-42, page 488 (1997).). It was found that the screening of the vacancies is very efficient and the screened vacancy potential should have a small influence on the properties. For instance, the density of states of A3C60 and A(3-x)C60 is practically identiacal.