PRECFOCK

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Revision as of 13:22, 15 February 2011 by Mmars (talk | contribs)

PRECFOCK = Low | Medium | Fast | Normal | Accurate
Default: PRECFOCK = Normal 

Description: PRECFOCK controls the FFT grids used in the exact exchange routines (Hartree-Fock and hybrid functionals).


PRECFOCK FFT-grid Augmentation charge Quality
Low Gcut identical to standard DFT large noise in forces/energy errors
Medium identical to std. FFT identical to standard DFT some noise in forces/good energy
Fast Gcut very soft augmentation chargea some noise in forces/good energy
Normal 3/2×Gcut soft augmentation chargeb accurate forces and energy
Accurate 2×Gcut soft augmentation chargeb very accurate forces and energy
a soft augmentation charge: radius for augmentation sphere is increased by factor 1.25 compared to default.

b very soft augmentation charge: radius is increased by factor 1.35 compared to default except for s-like charge, for the s-channel the radius of the augmentation sphere is increased by a factor 1.25.

where

with Ecut=ENCUT.

Related Tags and Sections

ENCUT, hybrid functionals, settings for specific hybrid functionals


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