LHFCALC

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

Description: LHFCALC specifies whether Hartree-Fock/DFT hybrid functional type calculations are performed.

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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

Example Calculations using this Tag

Bandgap of Si using different DFT+HF methods, Fcc Ni DOS with hybrid functional, MgO optimum mixing, Si bandstructure

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