A short introduction to the LDA+U approach to strongly correlated materials
Jaejun Yu
School of Physics and Center for Strongly Correlated Materials Research,
Seoul National University, Seoul 151-747, Korea
Despite successful applications of the density functional theory (DFT) to materials research, strong electron correlations have often become a bottleneck in the electronic structure calculation approach to understanding of various materials properties of transition metal oxides and other so-called strongly correlated materials. In this short tutorial, I will try to describe why the LDA (local density approximation) DFT approach has been so successful in the description of most real materials and when it fails to describe the essential physics of the correlated systems. Among various methods suggested to overcome the shortcomings of LDA, e.g., GW, SIC (self-interaction correction), LDA+U, and DMFT (dynamical mean field theory), I explain the basic idea behind the LDA+U method as a simple way to remedy for the LDA in treating the electron correlations arising from the strong on-site Coulomb interactions, and further introduce our recent development toward the O(N)-LDA+U method based on the localized pseudo-atomic orbital method.