The Dependence of the Density of States Tail on the Random Potential Statistics

The problem of the long‐range correlated random potential in a dielectric disordered system is studied by means of numerical solution of the saddle point equation. The obtained frequency dependence of the density of states displays the Halperin‐Lax behaviour at a correlation length small compared with the De'Broglie wavelength, it shows the Gaussian decreasing in the opposit limit and a relatively narrow region of a cross‐over Urbach‐like regime. The reasons are given in behalf of a predominant role of the fluctuations with the smallest correlation length possible for the system.