Self-interaction correction for an impurity resonance state in metals.

Abstract

The self-interaction correction (SIC) to the local-spin-density approximation (LSDA) is studied for a single impurity problem in metals. Although the impurity resonance state is a scattering state, we find that a localized orbital, for which the SIC should be considered, is obtained as in the case where the impurity state forms a real bound state. Model calculation shows that the exchange splitting of the virtual bound state is remarkably enhanced by SIC suggesting that the SIC-LSDA calculation achieves improvement of the LSDA results. A scheme to determine the occupation number of orbitals self-consistently in order to deal with the fractional occupation for metallic systems is also discussed.