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 4: / Line 4: @@
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 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., {{TAGO|ALGO|Damped}} ({{TAGO|IALGO|53}}) or {{TAGO|ALGO|All}} ({{TAGO|IALGO|58}}) in the {{FILE|INCAR}} file. You may also consider {{TAGO|ALGO|Normal}} which in combination with {{TAGO|LFOCKACE|TRUE}} (the default) can be a fast alternative. Do not use {{TAGO|ALGO|Fast}} which is not properly supported (note: no warning is printed).}}
+{{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).}}
-If the blocked-Davidson algorithm {{TAGO|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
+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
@@ Line 12: / Line 12: @@
 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:
+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}}.}}
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