PRECFOCK: Difference between revisions
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| Accurate || 2×G<sub>cut</sub> || soft augmentation charge<sup>b</sup> || very accurate forces and energy | | Accurate || 2×G<sub>cut</sub> || soft augmentation charge<sup>b</sup> || very accurate forces and energy | ||
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|colspan="4"|<sup>a</sup > | |colspan="4"|<sup>a</sup > radius for augmentation sphere is increased by factor 1.25 compared to default. | ||
<sup>b</sup> | <sup>b</sup> 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. | ||
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Revision as of 13:29, 15 February 2011
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 radius for augmentation sphere is increased by factor 1.25 compared to default. b 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
- [math]\displaystyle{ E_{\rm cut}=\frac{\hbar^2}{2m_e}G_{\rm cut}^2 }[/math]
with Ecut=ENCUT.
Related Tags and Sections
ENCUT, hybrid functionals, settings for specific hybrid functionals