Density of states of disordered systems with a finite correlation length

We consider a semiclassical formulation for the density of states (DOS) of disordered systems in any dimension. We show that this formulation becomes very accurate when the correlation length of the disorder potential is large. The disorder potential is piecewise constant and is not limited to the perturbative regime, where the disorder is small. The DOS is expressed in terms of a convolution of the disorder distribution function and the nondisordered DOS. We apply this formalism to evaluate the broadening of Landau levels and to calculate the specific heat in disordered systems.