NKRED: Difference between revisions
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Description: {{TAG|NKRED}} specifies an uniform reduction factor for the '''q'''-point grid representation of the exact exchange potential. | Description: {{TAG|NKRED}} specifies an uniform reduction factor for the '''q'''-point grid representation of the exact exchange potential. | ||
---- | ---- | ||
One may restrict the sum over '''q''' in the [[Hartree-Fock_and_HF/DFT_hybrid_functionals#VxFock|exchange potential]] to a subset, {'''q'''<sub>'''k'''</sub>}, of the full (''N''<sub> 1</sub>×''N''<sub> 2</sub>×''N''<sub> 3</sub>) '''k'''-point set, {'''k'''}, for which the following holds | |||
:<math> | |||
\mathbf{q_k} = \mathbf{b}_1 \frac{n_1 C_1}{N_1} + \mathbf{b}_2 \frac{n_2 C_2}{N_2} | |||
+ \mathbf{b}_3 \frac{n_3 C_3}{N_3},\quad(n_i=0,..,N_i-1) | |||
</math> | |||
where '''b'''<sub>1,2,3</sub> are the reciprocal lattice vectors of the primitive cell, | |||
and ''C''<sub> i</sub> is the integer grid reduction factor along reciprocal lattice direction | |||
'''b'''<sub> i</sub>. This leads to a reduction in the computational workload by a factor: | |||
:<math> | |||
\frac{1}{C_1 C_2 C_3} | |||
</math> | |||
== Related Tags and Sections == | == Related Tags and Sections == | ||
{{TAG|NKREDX}}, | {{TAG|NKREDX}}, | ||
Revision as of 16:23, 15 February 2011
NKRED = [integer]
Default: NKRED = 1
Description: NKRED specifies an uniform reduction factor for the q-point grid representation of the exact exchange potential.
One may restrict the sum over q in the exchange potential 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:
Related Tags and Sections
NKREDX, NKREDY, NKREDZ, EVENONLY, ODDONLY, downsampling, Hartree-Fock_and_HF/DFT_hybrid_functionals