Strong Coulomb Correlations in Electronic Structure Calculations

Materials where electrons show nearly localized rather than itinerant behaviour, such as the high-temperature superconducting copper oxides, or manganate oxides, are attracting interest due to their physical properties and potential applications. For these materials, the interaction between electrons, or electron correlation, plays an important role in describing their electronic strucuture, and the standard methods for the calculation of their electronic spectra based on the local density approximation (LDA) breakdown. This is the first attempt to describe recent approaches that go beyond the concept of the LDA, to successfully describe the electronic structure of narrow-band materials. 1. The GW Approximation and Vertex Corrections 2. The LDA+U Method: Screened Coulomb Interaction in the Mean-Field Approximation 3. LDSA and Self-Interaction Correction 4. Orbital Functionals in Density Functional Theory: The Optimized Effective Potential Method