LHFCALC

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.

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