NKREDY

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 b₂.

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One may restrict the sum over q in the Fock exchange potential (or one of its short range counterparts) to a subset, {q_k}, of the full (N₁×N₂×N₃) k-point set, {k}, for which the following holds

${\mathbf{q}}_{\mathbf{𝐤}}={\mathbf{𝐛}}_1\frac{n_1{C}_1}{N_1}+{\mathbf{𝐛}}_2\frac{n_2{C}_2}{N_2}+{\mathbf{𝐛}}_3\frac{n_3{C}_3}{N_3},(n_i=0,..,N_i-1)$

where b_1,2,3 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:

$\frac{1}{C_1{C}_2{C}_3}$

In case one sets NKRED, the grid reduction factors will be uniformly set to C₁=C₂=C₃=NKRED. If one wants to specify separate grid reduction factors for C₁, C₂, and C₃ one should use C₁=NKREDX, C₂=NKREDY, and C₃=NKREDZ, respectively.

Mind: there are circumstances under which NKRED and NKREDX,Y,Z should not be used!

Related Tags and Sections

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

Examples that use this tag

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