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This post is inspired by this post: What correlation effects are included in DFT?

The Kohn-Sham density functional theory (KS-DFT) are considered to be exact and can include all correlation effects in principle. However, if we want to apply DFT to perform practical calculations, we must make some approximations to the exchange-correlation energy, such as the famous local density approximation (LDA) and generalized gradient approximation (GGA).

My question is what correlation effects are included in KS-DFT with LDA and GGA?

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  • $\begingroup$ +1 for another interesting question by Jack! However, can you please fix up the links a little bit? This is something I often do for new users, but it would be nice if people could gradually get in the habit of making pristine posts themselves :) $\endgroup$
    – Nike Dattani
    Jan 23, 2021 at 4:37
  • $\begingroup$ I appreciate you fixing up the links here :) $\endgroup$
    – Nike Dattani
    Aug 14, 2021 at 17:35
  • $\begingroup$ @NikeDattani You are welcome, again. $\endgroup$
    – Jack
    Aug 15, 2021 at 23:39
  • $\begingroup$ Does this answer your question? What correlation effects are included in DFT? $\endgroup$
    – Susi Lehtola
    Aug 16, 2021 at 17:46
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    $\begingroup$ @SusiLehtola No. In fact, my question is inspired by your linked question. $\endgroup$
    – Jack
    Aug 16, 2021 at 23:25

1 Answer 1

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LDA only includes local density effects.

GGA also includes dependence on the gradient of the density.

Meta-GGAs include dependence on the Laplacian of the density and/or the local kinetic energy density.

Double hybrids include a mixture of post-Hartree-Fock correlation; typically either according to MP2 or RPA.

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