ENCUTFOCK

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Revision as of 19:48, 15 January 2017 by Karsai (talk | contribs)

ENCUTFOCK = [real] 

Default: none

Description: The ENCUTFOCK tag sets the energy cutoff that determines the FFT grids used by the Hartree-Fock routines.


The flag ENCUTFOCK is no longer supported in VASP.5.2.4 and newer versions. Please use PRECFOCK instead.


The only sensible value for ENCUTFOCK is ENCUTFOCK=0. This implies that the smallest possible FFT grid, which just encloses the cutoff sphere corresponding to the plane wave cutoff, is used. This accelerates the calculations by roughly a factor two to three, but causes slight changes in the total energies and some noise in the calculated forces. The FFT grid used internally in the exact exchange (Hartree-Fock) routines is written to the OUTCAR file. Simply search for lines starting with

FFT grid for exact exchange (Hartree Fock)


In many cases, a sensible approach is to determine the electronic and ionic groundstate using ENCUTFOCK=0, and to make one final total energy calculation without the flag ENCUTFOCK.

Related Tags and Sections

PRECFOCK, PREC, ENCUT, hybrid functionals, settings for specific hybrid functionals


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