Evaluation of some effective-medium theories for liquid and amorphous metals

We examine some recently proposed effective-medium theories for the electronic structure of strongly scattering liquid and amorphous metals. We employ a simple s-band tight-binding Hamiltonian and compare these theories with ``exact'' calculations on very large clusters. The Herglotz approximation proposed by Singh appears to be superior to the other recently proposed schemes, but does not do as well as the effective-medium approximation of Roth. Some recently reported approximations of Dagens are found to be unsatisfactory.