LHFCALC: Difference between revisions
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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. | ||
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 ([[density_mixing| | 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 | ||
LHFCALC = .TRUE. ; ALGO = Normal ; IMIX = 1 ; AMIX = a | LHFCALC = .TRUE. ; ALGO = Normal ; IMIX = 1 ; AMIX = a | ||
Revision as of 20:17, 1 February 2011
LHFCALC = .TRUE. | .FALSE.
Default: LHFCALC = .FALSE.
Description: LHFCALC specifies whether Hartree-Fock/DFT hybrid functional type calculations are performed.
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.