NKREDY: Difference between revisions

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{{TAGDEF|NKREDY|[integer]|1}}
{{TAGDEF|NKREDY|[integer]|1}}


Description: {{TAG|NKREDY}} specifies a reduction factor for the '''q'''-point grid representation of the exact exchange potential along reciprocal space direction '''b'''<sub> 1</sub>.
Description: {{TAG|NKREDY}} specifies a reduction factor for the '''q'''-point grid representation of the exact exchange potential along reciprocal space direction '''b'''<sub> 2</sub>.
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One may restrict the sum over '''q''' in the [[Hartree-Fock_and_HF/DFT_hybrid_functionals#VxFock|Fock exchange potential]] (or one of its [[Hartree-Fock_and_HF/DFT_hybrid_functionals#VxFockSR|short range counterparts]]) to a subset, {'''q'''<sub>'''k'''</sub>}, of the full (''N''<sub> 1</sub>&times;''N''<sub> 2</sub>&times;''N''<sub> 3</sub>)  '''k'''-point set, {'''k'''}, for which the following holds
One may restrict the sum over '''q''' in the [[Hartree-Fock_and_HF/DFT_hybrid_functionals#VxFock|Fock exchange potential]] (or one of its [[Hartree-Fock_and_HF/DFT_hybrid_functionals#VxFockSR|short range counterparts]]) to a subset, {'''q'''<sub>'''k'''</sub>}, of the full (''N''<sub> 1</sub>&times;''N''<sub> 2</sub>&times;''N''<sub> 3</sub>)  '''k'''-point set, {'''k'''}, for which the following holds

Revision as of 16:44, 15 February 2011

NKREDY = [integer]
Default: NKREDY = 1 

Description: NKREDY specifies a reduction factor for the q-point grid representation of the exact exchange potential along reciprocal space direction b 2.


One may restrict the sum over q in the Fock exchange potential (or one of its short range counterparts) to a subset, {qk}, of the full (N 1×N 2×N 3) k-point set, {k}, for which the following holds

where b1,2,3 are the reciprocal lattice vectors of the primitive cell, and C i is the integer grid reduction factor along reciprocal lattice direction b i. This leads to a reduction in the computational workload by a factor:

In case one sets NKRED, the grid reduction factors will be uniformly set to C 1=C 2=C 3=NKRED. If one wants to specify separate grid reduction factors for C 1, C 2, and C 3 one should use C 1=NKREDX, C 2=NKREDY, and C 3=NKREDZ, respectively.

Related Tags and Sections

NKRED, NKREDX, NKREDZ, EVENONLY, ODDONLY, downsampling, Hartree-Fock_and_HF/DFT_hybrid_functionals


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