LRHFCALC: Difference between revisions

Latest revision as of 12:38, 9 February 2026

LRHFCALC = .TRUE. | .FALSE.
Default: LRHFCALC = .FALSE.

Description: Switch on the decomposition of the exchange for the hybrid functionals using full Hartree-Fock exchange at long range.

If LRHFCALC=.TRUE. the exchange functional is decomposed into short-range LDA, PBE or PBEsol (GGA=CA, PE, PS, respectively) and long-range Hartree-Fock:

[math]\displaystyle{ E_{\mathrm{xc}}^{\mathrm{hybrid}}=a_{\mathrm{LR}} E_{\mathrm{x,LR}}^{\mathrm{HF}}(\mu) + E_{\mathrm{x,SR}}^{\mathrm{SL}}(\mu) + (1-a_{\mathrm{LR}})E_{\mathrm{x,LR}}^{\mathrm{SL}}(\mu) + E_{\mathrm{c}}^{\mathrm{SL}} }[/math]

The mixing [math]\displaystyle{ a_{\mathrm{LR}} }[/math] and screening [math]\displaystyle{ \mu }[/math] are controlled by the AEXX and HFSCREEN tags, respectively. The RSHXLDA or RSHXPBE functionals^[1]^[2]^[3] are examples of such functionals and their settings are shown on the page listing the hybrid functionals.

Mind:

If LRHFCALC=.TRUE., then LHFCALC=.TRUE. is automatically set.
If LRHFCALC=.TRUE., then AEXX=1 is automatically set, but AEXX can be set to another value.

Important: When AEXX=1 (the default for LRHFCALC=.TRUE.), the correlation [math]\displaystyle{ E_{\mathrm{c}}^{\mathrm{SL}} }[/math] is not included. However, it can be included by setting ALDAC=1.0 and AGGAC=1.0.

@@ Line 1: / Line 1: @@
 {{TAGDEF|LRHFCALC|.TRUE. {{!}} .FALSE. |.FALSE.}}
-Description: {{TAG|LRHFCALC}} specifies whether the only the long-range Hartree-Fock is used.
+Description: Switch on the decomposition of the exchange for the hybrid functionals using full Hartree-Fock exchange at long range.
 ----
-If one does not specifically request a particular hybrid functional (see {{TAG|AEXX}}, {{TAG|ALDAX}}, {{TAG|ALDAC}}, {{TAG|AGGAX}}, {{TAG|AGGAC}}, {{TAG|AMGGAX}}, {{TAG|AMGGAC}}, and the section on [[list_of_hybrid_functionals|settings for specific hybrid functionals]]) VASP will default to the [[list_of_hybrid_functionals#PBE0|PBE0 hybrid functional]].
+If {{TAG|LRHFCALC}}=.TRUE. the exchange functional is decomposed into short-range LDA, PBE or PBEsol ({{TAG|GGA}}{{=}}CA, PE, PS, respectively) and long-range Hartree-Fock:
-It is recommended to select a "direct optimization" algorithm for HF/DFT hybrid functonal type calculations, i.e., {{TAG|ALGO}}=Damped ({{TAG|IALGO}}=53) or {{TAG|ALGO}}=All ({{TAG|IALGO}}=58) in the {{FILE|INCAR}} file.
+:<math>E_{\mathrm{xc}}^{\mathrm{hybrid}}=a_{\mathrm{LR}} E_{\mathrm{x,LR}}^{\mathrm{HF}}(\mu) + E_{\mathrm{x,SR}}^{\mathrm{SL}}(\mu) + (1-a_{\mathrm{LR}})E_{\mathrm{x,LR}}^{\mathrm{SL}}(\mu) + E_{\mathrm{c}}^{\mathrm{SL}}</math>
-The blocked-Davidson algorithm {{TAG|ALGO}}=Normal is, with certain caveat, also supported, whereas calculations for the other algorithms ({{TAG|ALGO}}=Fast) are not properly supported (note: no warning is printed). The blocked-Davidson algorithm ({{TAG|ALGO}}=Normal) is generally rather slow, and in many cases the Pulay mixer will be unable to determine the proper ground-state. We hence recommend to select the blocked-Davidson algorithm only in combination with straight mixing or a Kerker like mixing (see the [[density_mixing|section on mixing]]). The following combination have been successfully applied for small and medium sized systems
+The mixing <math>a_{\mathrm{LR}}</math> and screening <math>\mu</math> are controlled by the {{TAG|AEXX}} and {{TAG|HFSCREEN}} tags, respectively. The RSHXLDA or RSHXPBE functionals{{cite|iikura:jcp:2001}}{{cite|gerber:cpl:2005}}{{cite|gerber:jcp:2007}} are examples of such functionals and
+their settings are shown on the [[list_of_hybrid_functionals|page listing the hybrid functionals]].
- {{TAG|LHFCALC}} = .TRUE. ; {{TAG|ALGO}} = Normal ; {{TAG|IMIX}} = 1 ; {{TAG|AMIX}} = a
+{{NB|mind|
+*If {{TAG|LRHFCALC}}{{=}}.TRUE., then {{TAG|LHFCALC}}{{=}}.TRUE. is automatically set.
-Decrease the parameter a until convergence is reached.
+*If {{TAG|LRHFCALC}}{{=}}.TRUE., then {{TAG|AEXX}}{{=}}1 is automatically set, but {{TAG|AEXX}} can be set to another value.}}
+{{NB|important|When {{TAG|AEXX}}{{=}}1 (the default for {{TAG|LRHFCALC}}{{=}}.TRUE.), the correlation <math>E_{\mathrm{c}}^{\mathrm{SL}}</math> is not included. However, it can be included by setting {{TAG|ALDAC}}{{=}}1.0 and {{TAG|AGGAC}}{{=}}1.0.}}
-In most cases, however, it is recommended to use the "Damped" algorithm with suitably chosen timestep. The following setup for the electronic optimization works reliably in most cases:
- {{TAG|LHFCALC}} = .TRUE. ; {{TAG|ALGO}} = Damped ; {{TAG|TIME}} = 0.5
-If convergence is not obtained, it is recommended to reduce the timestep {{TAG|TIME}}.
 == Related tags and articles ==
+{{TAG|LHFCALC}},
+{{TAG|HFSCREEN}},
 {{TAG|AEXX}},
-{{TAG|ALDAX}},
+{{TAG|LMODELHF}},
-{{TAG|ALDAC}},
+{{TAG|LTHOMAS}},
-{{TAG|AGGAX}},
+[[list_of_hybrid_functionals|list of hybrid functionals]],
-{{TAG|AGGAC}},
+[[Hybrid_functionals:_formalism|Hybrid functionals: formalism]]
-{{TAG|AMGGAX}},
-{{TAG|AMGGAC}},
-{{TAG|HFSCREEN}},
-[[list_of_hybrid_functionals|settings for specific hybrid functionals]]
-{{sc|LHFCALC|Examples|Examples that use this tag}}
+{{sc|LRHFCALC|Examples|Examples that use this tag}}
 ----
 [[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]]