We develop a density-matrix correlation-energy functional suitable for treating impurity sites with strong electronic correlations. The functional is based on a rigorous theorem about the form of such functionals as well as an exact inequality for the exchange-correlation energy. It is validated by comparison with exact results for small clusters, and is used to treat the electronic properties of an Anderson impurity in a random alloy.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2001