Application of a self-consistent LSDA-CPA method to the Mott-Anderson transition in doped semiconductors

A comprehensive theoretical study of the metal-insulator transition in doped semiconductors demands that the effect of electron-electron interactions and the effect of disorder be treated on an equal footing. The local-spin-density-approximation-coherent-potential-approximation method [K. Koepernik , Phys. Rev. B 58, 6944 (1998)] is well suited to such a study. We discuss the relevance of this method and define, within the effective-mass approximation, a pseudoalloy HxE1-x of hydrogenic atoms H and vacancies E. A first result is the opening of a gap between the (spin-polarized) lower impurity band and the upper impurity band as a function of the lattice parameter and of the dilution x which mimics the disorder. We find that the disorder only slightly affects the critical concentration of the gap opening.