XC C: Difference between revisions

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{{DISPLAYTITLE:XC_C}}
{{DISPLAYTITLE:XC_C}}
{{TAGDEF|XC_C|[real] | 1.0 1.0 ...}}
{{TAGDEF|XC_C|[real array] | 1.0*NXC}}


Description: {{TAG|XC_C}} allows to specify the factors that multiply the functionals specified with the {{TAG|XC}}.
Description: Multiplication factors for the components of the functional given by the {{TAG|XC}} tag.
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For many of the functionals implemented in the library of exchange-correlation functionals Libxc{{cite|marques:cpc:2012}}{{cite|lehtola:sx:2018}}{{cite|libxc}} it is possible to modify the parameters if one does not want to use the default values. If a functional from Libxc has parameters that can be modified, then they are listed in {{FILE|OUTCAR}} below "Parameters of Libxc functionals:" as P<math>n</math> (<math>n=1, 2, \ldots</math>). {{TAG|LIBXC1_Pn}} and {{TAG|LIBXC2_Pn}} are for the functionals called with {{TAG|LIBXC1}} and {{TAG|LIBXC2}}, respectively.
{{TAG|XC_C}} sets the factors that multiply each component of the functional specified with the {{TAG|XC}} tag. The number of values specified with {{TAG|XC_C}} has to be equal to the number of functional components set with {{TAG|XC}} (NXC). Examples of how to use {{TAG|XC_C}} are provided at {{TAG|XC}}.
{{NB|mind|
*{{TAG|XC_C}} is available since VASP.6.4.3.
*The {{TAG|XC_C}} tag can be used together with the {{TAG|ALDAX}}, {{TAG|ALDAC}}, {{TAG|AGGAX}}, {{TAG|AGGAC}}, {{TAG|AMGGAX}}, and {{TAG|AMGGAC}} tags that can be used when {{TAG|LHFCALC}}{{=}}.TRUE.. Such examples are provided at {{TAG|XC}}.
}}


An example is given below for the GGA PBE functional{{cite|perdew:prl:1996}} where the default parameters <math>\mu=0.21951</math> in exchange and <math>\beta=0.066725</math> in correlation are changed to <math>\mu=10/81\approx0.12345679</math> and <math>\beta=0.046</math> to get the PBEsol functional{{cite|perdew:prl:2008}} (of course, the simpler way to use PBEsol from Libxc would be to call it directly with {{TAG|LIBXC1}}=GGA_X_PBE_SOL and {{TAG|LIBXC2}}=GGA_C_PBE_SOL).
== Related tags and articles ==
{{TAG|GGA}} = LIBXC
{{TAG|LIBXC1}} = GGA_X_PBE # or 101
{{TAG|LIBXC2}} = GGA_C_PBE # or 130
[[LIBXC1_Pn|LIBXC1_P2]] = 0.12345679
[[LIBXC2_Pn|LIBXC2_P1]] = 0.046
{{NB|mind|The {{TAG|ALDAX}}, {{TAG|ALDAC}}, {{TAG|AGGAX}}, {{TAG|AGGAC}}, {{TAG|AMGGAX}}, and {{TAG|AMGGAC}} tags are ignored if the Libxc functional is an exchange-correlation functional (those with a tag that contains XC)}}


For Libxc functionals that are the semilocal component of a hybrid functional, i.e. those with a tag that starts with HYB ({{TAG|LHFCALC}}=.TRUE. will be set automatically if such a functional is selected), the following explains how it works for the mixing and screening parameters:
{{TAG|XC}},
*Mixing parameter:
**It is usually one of the parameters {{TAG|LIBXC1_Pn}}, and can therefore be modified.
**For HYB_GGA_XC_PBEH, HYB_GGA_XC_B1WC, HYB_GGA_XC_HSE03, HYB_GGA_XC_HSE06, HYB_GGA_XC_HSE12, and HYB_GGA_XC_HSE12S, the value of {{TAG|AEXX}} (even if not specified explicitly in {{FILE|INCAR}}) will be used and automatically passed to the corresponding parameter in Libxc. On the other hand, if this corresponding parameter ({{TAG|LIBXC1_Pn}}) is specified in {{FILE|INCAR}}, then it will be used (instead of {{TAG|AEXX}}), however note that it will be only for the semilocal component of the hybrid functional and not for the exact exchange that will still use {{TAG|AEXX}}.
**For all hybrid functionals except those listed just above, {{TAG|AEXX}} will not be considered for the semilocal component of the hybrid functional, but only for the exact exchange component. Therefore, a particular choice for the mixing parameter has to be done by specifying both {{TAG|AEXX}} (for the exact exchange) and the appropriate {{TAG|LIBXC1_Pn}} (for the semilocal component).
**The {{TAG|ALDAX}}, {{TAG|ALDAC}}, {{TAG|AGGAX}}, {{TAG|AGGAC}}, {{TAG|AMGGAX}}, and {{TAG|AMGGAC}} tags are ignored if the Libxc functional is an hybrid functional (those with a tag that starts with HYB).
*Screening parameter:
**It is usually one of the parameters {{TAG|LIBXC1_Pn}} if it is a screened functional, and can therefore be modified.
**For HYB_GGA_XC_HSE03, HYB_GGA_XC_HSE06, HYB_GGA_XC_HSE12, and HYB_GGA_XC_HSE12S, the value of {{TAG|HFSCREEN}} (even if not specified explicitly in {{FILE|INCAR}}) will be used and automatically passed to the corresponding parameter in Libxc. On the other hand, if this corresponding parameter ({{TAG|LIBXC1_Pn}}) is specified in {{FILE|INCAR}}, then it will be used (instead of {{TAG|HFSCREEN}}), however note that it will be only for the semilocal component of the hybrid functional and not for the exact exchange that will still use {{TAG|HFSCREEN}}.
**For all hybrid functionals except those listed just above, {{TAG|HFSCREEN}} will not be considered for the semilocal component of the hybrid functional, but only for the exact exchange component. Therefore, a particular choice for the screening parameter has to be done by specifying both {{TAG|HFSCREEN}} (for the exact exchange) and the appropriate {{TAG|LIBXC1_Pn}} (for the semilocal component).
 
== Related tags and articles ==
{{TAG|LIBXC1}},
{{TAG|LIBXC2}},
{{TAG|LIBXC2_Pn}},
{{TAG|LTBOUNDLIBXC}},
{{TAG|GGA}},
{{TAG|GGA}},
{{TAG|METAGGA}},
{{TAG|METAGGA}},
{{TAG|LHFCALC}},
{{TAG|AEXX}},
{{TAG|ALDAX}},
{{TAG|ALDAX}},
{{TAG|ALDAC}},
{{TAG|ALDAC}},
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{{TAG|AGGAC}},
{{TAG|AGGAC}},
{{TAG|AMGGAX}},
{{TAG|AMGGAX}},
{{TAG|AMGGAC}},
{{TAG|AMGGAC}}
[[list_of_hybrid_functionals|List of hybrid functionals]]
 
 
{{sc|LIBXC1_Pn|Examples|Examples that use this tag}}


== References ==
{{sc|XC_C|Examples|Examples that use this tag}}
<references/>


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[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]][[Category:meta-GGA]][[Category:Hybrid_functionals]]
[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]][[Category:meta-GGA]][[Category:Hybrid_functionals]]

Latest revision as of 10:51, 19 March 2024

XC_C = [real array]
Default: XC_C = 1.0*NXC 

Description: Multiplication factors for the components of the functional given by the XC tag.


XC_C sets the factors that multiply each component of the functional specified with the XC tag. The number of values specified with XC_C has to be equal to the number of functional components set with XC (NXC). Examples of how to use XC_C are provided at XC.

Mind:

Related tags and articles

XC, GGA, METAGGA, ALDAX, ALDAC, AGGAX, AGGAC, AMGGAX, AMGGAC

Examples that use this tag