LHFCALC: Difference between revisions
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{{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).}} | {{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 {{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 | 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 | {{TAG|LHFCALC}} = .TRUE. ; {{TAG|ALGO}} = Normal ; {{TAG|IMIX}} = 1 ; {{TAG|AMIX}} = a | ||
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Decrease the parameter a until convergence is reached. | 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 | {{TAG|LHFCALC}} = .TRUE. ; {{TAG|ALGO}} = Damped ; {{TAG|TIME}} = 0.5 | ||
If convergence is not obtained, it is recommended to reduce the timestep {{TAG|TIME}}. | 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 == | == Related tags and articles == | ||
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).
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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.
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Related tags and articles
AEXX, ALDAX, ALDAC, AGGAX, AGGAC, AMGGAX, AMGGAC, HFSCREEN, LTHOMAS, LRHFCALC, LFOCKACE, List of hybrid functionals, Hybrid functionals: formalism