LHFCALC: Difference between revisions
No edit summary |
No edit summary |
||
| Line 3: | Line 3: | ||
Description: {{TAG|LHFCALC}} specifies whether Hartree-Fock/DFT hybrid functional type calculations are performed. | Description: {{TAG|LHFCALC}} specifies whether Hartree-Fock/DFT hybrid functional type calculations are performed. | ||
---- | ---- | ||
If one does not specifically request a particular hybrid functional (see {{TAG|AEXX}}, {{TAG|AGGAX}}, {{TAG|AGGAC}}, {{TAG|ALDAC}}, and the section on [[specific_hybrid_functionals|settings for specific hybrid functionals]]) VASP will default to the [[specific_hybrid_functionals#PBE0|PBE0 hybrid functional]]. | |||
It is recommended to select an "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. | It is recommended to select an "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. | ||
| Line 16: | Line 18: | ||
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}}. | ||
== Related Tags and Sections == | == Related Tags and Sections == | ||
Revision as of 20:29, 1 February 2011
LHFCALC = .TRUE. | .FALSE.
Default: LHFCALC = .FALSE.
Description: LHFCALC specifies whether Hartree-Fock/DFT hybrid functional type calculations are performed.
If one does not specifically request a particular hybrid functional (see AEXX, AGGAX, AGGAC, ALDAC, and the section on settings for specific hybrid functionals) VASP will default to the PBE0 hybrid functional.
It is recommended to select an "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.
The blocked-Davidson algorithm ALGO=Normal is, with certain caveat, also supported, whereas calculations for the other algorithms (ALGO=Fast) are not properly supported (note: no warning is printed). The blocked-Davidson algorithm (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 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 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.
Related Tags and Sections
AEXX, AGGAX, AGGAC, ALDAC, hybrid functionals, settings for specific hybrid functionals