deletions | additions       diff --git a/introduction.tex b/introduction.tex  index 6c99bc1..e273a63 100644  --- a/introduction.tex  +++ b/introduction.tex 
...
The basic feature of correlated materials is their electrons cannot be described as non-interacting particles, posing special challenges for theory. Often, this occurs because the material contains atoms with partially-filled $d$ or $f$ orbitals. The electrons occupying these orbitals retain a strong atomic-like character to their behavior, which when combined with the band-like behavior of the remaining electrons, makes for a challenging problem. Consequently current implementations of DFT cannot describe their properties accurately. This led to the development of extensions to DFT such as LDA+U, and entirely more sophisticated approaches such as dynamical mean field theory (DMFT) and the GW approximation.  TODO: Describe the intersection of materials design with correlated materials. Also describe the need for large computable databases.  % Only LDA+U can produce energies at scale.  % Materials design also necessarily involves handling and organizing large bodies of data since the process of check => machine learning.