# Density Functional Theory Density fictional theory (commonly abbreviated DFT, which is a very dangerous acronym to make a typo with) is a computational way to model quantum systems. Some constraints[from Wikipedia:](https://en.wikipedia.org/wiki/Density_functional_theory) `Despite recent improvements, there are still difficulties in using density functional theory to properly describe: [intermolecular interactions](https://en.wikipedia.org/wiki/Intermolecular_force) (of critical importance to understanding chemical reactions), especially [van der Waals forces](https://en.wikipedia.org/wiki/Van_der_Waals_force) (dispersion); charge transfer excitations; transition states, global potential energy surfaces, dopant interactions and some [strongly correlated](https://en.wikipedia.org/wiki/Strongly_correlated_material) systems; and in calculations of the [band gap](https://en.wikipedia.org/wiki/Band_gap) and [ferromagnetism](https://en.wikipedia.org/wiki/Ferromagnetism) in [semiconductors](https://en.wikipedia.org/wiki/Semiconductor) . [[1]](https://en.wikipedia.org/wiki/Density_functional_theory#cite_note-dftmag-1) ` Created: ~1970s [Web URL for this note](http://notes.benjaminreinhardt.com/Density+Functional+Theory) [Comment on this note](http://via.hypothes.is/http://notes.benjaminreinhardt.com/Density+Functional+Theory)