Local Density Approximation Method for Correlated Metals

While the Local Density Approximation LDA+U method is well established for Mott insualtors with well localized orbitals, its application to weakly correlated metals is questionable. By extending the Stoner approach to LDA+U, we show that LDA+U enhances the Stoner factor, while reducing the density of states. The most important correlation effects in metals, fluctuation induced mass renormalization, and suppression of the Stoner factor are missing from LDA+U. For moderately correlated metals we derive a version of LDA+U which can be formulated as a constrained density functional theory. We compare the LDA+U and LDA+DMFT on concrete examples, including the controversial case of magnetism in FeAl.