LHFCALC= .TRUE. | .FALSE.
The flag specifies, whether Hartree-Fock type calculations are performed. At the moment, it is recommended to select an all bands simultaneous algorithm, i.e. ALGO=Damped (IALGO=53) or ALGO=All (IALGO=58) in the INCAR file (see Sec. 6.46 6.47).
The blocked Davidson algorithm ALGO=Normal is, with certain caveat, also supported, whereas calculations for the other algorithms (ALGO=Fast) are not currently 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. The following combination have been successfully applied for small and medium sized systems
LHFCALC = .TRUE. ; ALGO = Normal ; IMIX = 1 ; AMIX = aDecrease 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 = 0.4If convergence is not obtained, it is recommended to reduce the timestep TIME.