ENCUTFOCK: Difference between revisions
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Default: none | Default: none | ||
Description: The {{TAG|ENCUTFOCK}} tag sets the energy cutoff that determines the FFT grids used by the Hartree-Fock routines. | |||
---- | |||
The flag {{TAG|ENCUTFOCK}} is no longer supported in VASP.5.2.4 and newer versions. | The flag {{TAG|ENCUTFOCK}} is no longer supported in VASP.5.2.4 and newer versions. | ||
Please use {{TAG|PRECFOCK}} instead. | Please use {{TAG|PRECFOCK}} instead. | ||
The only sensible value for {{TAG|ENCUTFOCK}} is {{TAG|ENCUTFOCK}}=0. | The only sensible value for {{TAG|ENCUTFOCK}} is {{TAG|ENCUTFOCK}}=0. | ||
This implies that the smallest possible FFT grid, which just encloses the cutoff sphere | This implies that the smallest possible FFT grid, which just encloses the cutoff sphere | ||
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but causes slight changes in the total energies and some noise in the calculated forces. | 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 | The FFT grid used internally in the exact exchange (Hartree-Fock) routines | ||
is written to the OUTCAR file. Simply search for lines starting with | is written to the {{TAG|OUTCAR}} file. Simply search for lines starting with | ||
FFT grid for exact exchange (Hartree Fock) | FFT grid for exact exchange (Hartree Fock) | ||
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using {{TAG|ENCUTFOCK}}=0, and to make one final total energy calculation | using {{TAG|ENCUTFOCK}}=0, and to make one final total energy calculation | ||
without the flag {{TAG|ENCUTFOCK}}. | without the flag {{TAG|ENCUTFOCK}}. | ||
== Related tags and articles == | |||
{{TAG|PRECFOCK}}, | |||
{{TAG|PREC}}, | |||
{{TAG|ENCUT}}, | |||
[[list_of_hybrid_functionals|List of hybrid functionals]], | |||
[[Hybrid_functionals:_formalism|Hybrid functionals: formalism]] | |||
{{sc|ENCUTFOCK|Examples|Examples that use this tag}} | |||
---- | |||
[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]] | |||
Latest revision as of 09:14, 18 October 2023
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 articles
PRECFOCK, PREC, ENCUT, List of hybrid functionals, Hybrid functionals: formalism