Estimating average densities of states for disordered systems

Abstract

The definition of the average electronic density of states as the volume average of the local density of states, or of the projected density of states for localized orbitals, suggests that this quantity should be approximated by the average of the projected densities of states for a sample of the orbitals. Contrary to this, it is shown computationally that for typical two-dimensional disordered systems, the average density of states is better approximated by the projected density of states for a state which is a combination of orbitals having random phases. This result can be understood in terms of electron localization and leads to a hypothesis about the average density of states for three-dimensional disordered systems.