LHFCALC: Difference between revisions

Latest revision as of 11:39, 9 February 2026

LHFCALC = .TRUE. | .FALSE.
Default: LHFCALC = .FALSE.

Description: LHFCALC specifies whether a Hartree-Fock/DFT hybrid functional type calculation is performed.

If one does not specifically request a particular hybrid functional (see AEXX, ALDAX, ALDAC, AGGAX, AGGAC, AMGGAX, AMGGAC, and the list_of_hybrid_functionals) VASP will default to the PBE0 hybrid functional.

Tip: For the most reliable convergence, select a "direct optimization" algorithm for HF/DFT hybrid functonal type calculations, i.e., ALGO = Damped (IALGO = 53) or ALGO = All (IALGO = 58) in the INCAR file. You may also consider ALGO = Normal which in combination with LFOCKACE = TRUE (the default) can be a fast alternative. Do not use ALGO = Fast which is not properly supported (note: no warning is printed).

If the blocked-Davidson algorithm ALGO = Normal is used, 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 section on mixing). The following combination have been successfully applied for small and medium-sized systems

LHFCALC = .TRUE. ; ALGO = Normal ; IMIX = 1 ; AMIX = a

Decrease the parameter a until convergence is reached.

In most cases, however, it is recommended to use the "Damped" algorithm with a suitably chosen timestep. The following setup for the electronic optimization works reliably in most cases:

LHFCALC = .TRUE. ; ALGO = Damped ; TIME = 0.5

If convergence is not obtained, it is recommended to reduce the timestep TIME.

Mind: The stress tensor is not calculated by default for LHFCALC = .TRUE. (i.e., ISIF = 0) as it is expensive for hybrid functionals. It can be turned on by setting ISIF = 2.

@@ Line 1: / Line 1: @@
 {{TAGDEF|LHFCALC|.TRUE. {{!}} .FALSE. |.FALSE.}}
-Description: {{TAG|LHFCALC}} specifies whether Hartree-Fock/DFT hybrid functional type calculations are performed.
+Description: {{TAG|LHFCALC}} specifies whether a Hartree-Fock/DFT hybrid functional type calculation is performed.
 ----
+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 [[list_of_hybrid_functionals|list_of_hybrid_functionals]]) VASP will default to the [[list_of_hybrid_functionals#PBE0|PBE0 hybrid functional]].
+{{NB|tip|For the most reliable convergence, 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. You may also consider {{TAG|ALGO|Normal}} which in combination with {{TAG|LFOCKACE|TRUE}} (the default) can be a fast alternative. Do not use {{TAG|ALGO|Fast}} which is not properly supported (note: no warning is printed).}}
-== Related Tags and Sections ==
+If the blocked-Davidson algorithm {{TAG|ALGO|Normal}} is used, 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
+ {{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 a 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}}.
+{{NB|mind|The stress tensor is not calculated by default for {{TAG|LHFCALC|.TRUE.}} (i.e., {{TAG|ISIF|0}}) as it is expensive for hybrid functionals. It can be turned on by setting {{TAG|ISIF|2}}.}}
+== Related tags and articles ==
+{{TAG|AEXX}},
+{{TAG|ALDAX}},
+{{TAG|ALDAC}},
+{{TAG|AGGAX}},
+{{TAG|AGGAC}},
+{{TAG|AMGGAX}},
+{{TAG|AMGGAC}},
+{{TAG|HFSCREEN}},
+{{TAG|LTHOMAS}},
+{{TAG|LRHFCALC}},
+{{TAG|LFOCKACE}},
+[[list_of_hybrid_functionals|List of hybrid functionals]],
+[[Hybrid_functionals:_formalism|Hybrid functionals: formalism]]
+{{sc|LHFCALC|Examples|Examples that use this tag}}
 ----
-[[The_VASP_Manual|Contents]]
-[[Category:INCAR]][[Category:Hybrids]]
+[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]]