Density-Corrected Density Functional Theory

In the early days of DFT, non-self-consistent Kohn-Sham energy was often evaluated upon Hartree-Fock (HF) densities as a way to test new approximations. This method was called HF-DFT. It has been discovered that in some cases, HF-DFT actually gave more accurate answers when compared to self-consistent DFT calculations.

By using a scheme proposed on Ref. 141, we found that DFT calculations can be categorized into two different types of calculations. First we decompose the error of an approximate functional into two parts: error from the functional (functional error), and error from the density (density-driven error). For most calculations, functional error is dominant, and here self-consistent DFT is usually better than non-self consistent DFT on more accurate densities (which we call density corrected DFT (DC-DFT)).

Unlike these 'normal' calculations, there is a class of calculations where the density-driven error is much larger, so DC-DFT give better a result than self-consistent DFT . We classify these calculations as 'abnormal'. HF-DFT is a simple implementation of DC-DFT and we found that a small HOMO-LUMO gap is an indicator of abnormal calculation, thus, HF-DFT would perform better in such cases.

We are trying to determine which are abnormal cases among well-known problematic cases in DFT, and applying DC-DFT to solve these challenging problems.

[149] Ions in solution: Density corrected density functional theory (DC-DFT) Min-Cheol Kim, Eunji Sim, Kieron Burke, The Journal of Chemical Physics 140, 18A528 (2014). [bibtex] [pdf]
[141] Understanding and reducing errors in density functional calculations Min-Cheol Kim, Eunji Sim, Kieron Burke, Phys. Rev. Lett. 111, 073003 (2013). [supplementary information] [bibtex] [pdf]
[131] Communication: Avoiding unbound anions in density functional calculations Min-Cheol Kim, Eunji Sim, Kieron Burke, J. Chem. Phys. 134, 171103 (2011). [bibtex] [pdf]
[127] Finding electron affinities with approximate density functionals Donghyung Lee, Kieron Burke, Molecular Physics 108, 2687-2701 (2010). [bibtex] [pdf]
[126] Accuracy of Electron Affinities of Atoms in Approximate Density Functional Theory Donghyung Lee, Filipp Furche, Kieron Burke, J. Phys. Chem. Lett. 1, 2124-2129 (2010). [bibtex] [pdf]

We graciously acknowledge support from the global research network grant (No. NRF- 2010-220-C00017), the national research foundation [2012R1A1A2004782 (E. S.)], and NSF CHE-1112442.