Density functional theory (DFT) is a formally exact re-writing of
quantum mechanics with the electron density ρ as the basic variable instead of the
wavefunction. The reduced computational cost of this approach lead to DFT becoming the most popular method of
quantum chemistry from the mid-1990s onwards.
The DFT Difference
Early Models
The first true density functional theory was developed by Thomas and Fermi in the 1920's.
Kohn-Sham Theory
References
[1] P. Hohenberg and W. Kohn, Phys. Rev. 136 (1964) B864.
[2] W. Kohn and L. J. Sham, Phys. Rev. 140 (1965) A1133.
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