XC: Difference between revisions

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{{NB| important| VASP recalculates the exchange-correlation energy inside the PAW sphere and corrects the atomic energies given by the {{FILE|POTCAR}} file. For this to work, the original LEXCH tag must not be modified in the {{FILE|POTCAR}} file.}}
{{NB| important| VASP recalculates the exchange-correlation energy inside the PAW sphere and corrects the atomic energies given by the {{FILE|POTCAR}} file. For this to work, the original LEXCH tag must not be modified in the {{FILE|POTCAR}} file.}}


A few points should be noted:
*The LIBXC option (or just LI) allows to use a LDA or GGA functional from the library of exchange-correlation functionals Libxc{{cite|marques:cpc:2012}}{{cite|lehtola:sx:2018}}{{cite|libxc}}. Along with {{TAG|GGA}}=LIBXC, it is also necessary to specify the {{TAG|LIBXC1}} and {{TAG|LIBXC2}} tags that specify the particular functional. Note that it is necessary to have [[Makefile.include#Libxc_.28optional.29|Libxc >= 5.2.0 installed]] and VASP.6.3.0 or higher compiled with [[Precompiler_options#-DUSELIBXC|precompiler options]].
*When the OR, BO, MK, ML or CX GGA is used in combination with the nonlocal vdW-DF functional of Dion ''et al.''{{cite|dion:prl:2004}}, the GGA component of the correlation should in principle be turned off with {{TAG|AGGAC}}=0 (see {{TAG|nonlocal vdW-DF functionals}}).
<!--
*The options in the last table allow to select range-separated ACFDT calculations, where a short-range local (DFT-like) exchange and correlation kernel is added to the long-range exchange and RPA correlation energy.
-->


The possible options for the {{TAG|GGA}} tag are:
 
<!--
:'''No functional:'''
:{| border="1" cellspacing="0" cellpadding="5"
|-
|CO  || No exchange-correlation
|-
|}
-->




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{{TAG|AGGAX}},
{{TAG|AGGAX}},
{{TAG|AGGAC}},
{{TAG|AGGAC}},
{{TAG|GGA}},
{{TAG|METAGGA}}
{{TAG|METAGGA}}


{{sc|GGA|Examples|Examples that use this tag}}
{{sc|XC|Examples|Examples that use this tag}}


== References ==
== References ==

Revision as of 15:01, 29 January 2024

XC = Combination of functionals 

Description: XC specifies a LDA, GGA exchange-correlation functional.

This tag was added to perform GGA calculations with pseudopotentials generated with conventional LDA reference configurations.

Important: VASP recalculates the exchange-correlation energy inside the PAW sphere and corrects the atomic energies given by the POTCAR file. For this to work, the original LEXCH tag must not be modified in the POTCAR file.



Related tags and articles

LIBXC1, LIBXC2, ALDAX, ALDAC, AGGAX, AGGAC, GGA, METAGGA

Examples that use this tag

References



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