Dynamics of Disordered Alloys and Glasses

Abstract

A formalism is presented for the calculation of the spectrum of normal modes of a disordered solid by means of a perturbation theory that takes a mean-field model as its unperturbed system. A transformation is used that allows the long-range correlations in the low-frequency vibrational modes to be accurately taken into account. In the special case of a random substitutional alloy, a result is found which reduces to those of other workers when the limit of small mass difference of the constituents or low concentration is taken. Some aspects of the application of the theory to amorphous systems are also discussed.