LRHFCALC: Difference between revisions

Latest revision as of 14:27, 5 September 2025

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, like RSHXLDA or RSHXPBE.

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, like for instance in RSHXLDA or RSHXPBE.^[1]^[2]^[3] The screening parameter is specified by means of the HFSCREEN tag.

The setting of the RSHXLDA and RSHXPBE functionals is 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.

@@ Line 1: / Line 1: @@
-{{TAGDEF|LHFCALC|.TRUE. {{!}} .FALSE. |.FALSE.}}
+{{TAGDEF|LRHFCALC|.TRUE. {{!}} .FALSE. |.FALSE.}}
-Description: {{TAG|LHFCALC}} specifies whether a Hartree-Fock/DFT hybrid functional type calculation is performed.
+Description: Switch on the decomposition of the exchange for the hybrid functionals using full Hartree-Fock exchange at long range, like [[Hybrid_functionals:_formalism#Error_function_screening_with_long-range_Hartree-Fock_exchange|RSHXLDA or RSHXPBE]].
 ----
-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, like for instance in [[Hybrid_functionals:_formalism#Error_function_screening_with_long-range_Hartree-Fock_exchange|RSHXLDA or RSHXPBE]].{{cite|iikura:jcp:2001}}{{cite|gerber:cpl:2005}}{{cite|gerber:jcp:2007}} The screening parameter is specified by means of the {{TAG|HFSCREEN}} tag.
-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.
+The setting of the RSHXLDA and RSHXPBE functionals is shown on the [[list_of_hybrid_functionals|page listing the hybrid functionals]].
+{{NB|mind|
-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
+*If {{TAG|LRHFCALC}}{{=}}.TRUE., then {{TAG|LHFCALC}}{{=}}.TRUE. is automatically set.
+*If {{TAG|LRHFCALC}}{{=}}.TRUE., then {{TAG|AEXX}}{{=}}1 is automatically set, but {{TAG|AEXX}} can be set to another value.}}
- {{TAG|LHFCALC}} = .TRUE. ; {{TAG|ALGO}} = Normal ; {{TAG|IMIX}} = 1 ; {{TAG|AMIX}} = a
-Decrease the parameter a until convergence is reached.
-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|LTHOMAS}},
-{{TAG|ALDAC}},
+[[list_of_hybrid_functionals|list of hybrid functionals]],
-{{TAG|AGGAX}},
+[[Hybrid_functionals:_formalism|Hybrid functionals: formalism]]
-{{TAG|AGGAC}},
-{{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]]