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Physical Origin of the One-Quarter Exact Exchange in Density Functional Theory

Bernardi, Marco (2020) Physical Origin of the One-Quarter Exact Exchange in Density Functional Theory. Journal of Physics: Condensed Matter, 32 (38). Art. No. 385501. ISSN 0953-8984. doi:10.1088/1361-648x/ab9409.

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Exchange interactions are a manifestation of the quantum mechanical nature of the electrons and play a key role in predicting the properties of materials from first principles. In density functional theory (DFT), a widely used approximation to the exchange energy combines fractions of density-based and Hartree–Fock (exact) exchange. This so-called hybrid DFT scheme is accurate in many materials, for reasons that are not fully understood. Here we show that a 1/4 fraction of exact exchange plus a 3/4 fraction of density-based exchange is compatible with a correct quantum mechanical treatment of the exchange energy of an electron pair in the unpolarized electron gas. We also show that the 1/4 exact-exchange fraction mimics a correlation interaction between doubly-excited electronic configurations. The relation between our results and trends observed in hybrid DFT calculations is discussed, along with other implications.

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URLURL TypeDescription Paper
Bernardi, Marco0000-0001-7289-9666
Alternate Title:On the Physical Origin of the 1/4 Exact Exchange in Density Functional Theory
Additional Information:© 2020 IOP Publishing Ltd. Received 6 March 2020; Revised 7 May 2020; Accepted 18 May 2020; Accepted Manuscript online 18 May 2020. M.B. thanks Nicola Marzari and Fernando Brandao for fruitful discussions. M.B. also thanks Megan Schill for discussion and for help with the initial stage of this project. This work was supported by the National Science Foundation under Grant CAREER no. CAREER-1750613.
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Issue or Number:38
Record Number:CaltechAUTHORS:20181112-071407515
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Official Citation:Marco Bernardi 2020 J. Phys.: Condens. Matter 32 385501
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90820
Deposited By: Tony Diaz
Deposited On:13 Nov 2018 19:42
Last Modified:12 Jul 2022 16:42

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