EVENONLY: Difference between revisions
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Description: {{TAG|EVENONLY}}=.TRUE. selects a subset of '''k'''-points for the representation of the Fock exchange potential, with ''C''<sub>1</sub>=''C''<sub>2</sub>=''C''<sub>3</sub>=1, and ''n''<sub>1</sub>+''n''<sub>2</sub>+''n''<sub>3</sub> even. | Description: {{TAG|EVENONLY}}=.TRUE. selects a subset of '''k'''-points for the representation of the Fock exchange potential, with ''C''<sub>1</sub>=''C''<sub>2</sub>=''C''<sub>3</sub>=1, and ''n''<sub>1</sub>+''n''<sub>2</sub>+''n''<sub>3</sub> even. | ||
---- | ---- | ||
One may restrict the sum over '''q''' in the [[ | One may restrict the sum over '''q''' in the [[:Category:Hybrids|Fock exchange potential]] (or one of its [[:Category:Hybrids|short range counterparts]]) 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> | :<math> | ||
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{{TAG|EVENONLY}}=.TRUE. selects a subset of '''k'''-points with ''C''<sub>1</sub>=''C''<sub>2</sub>=''C''<sub>3</sub>=1, and ''n''<sub>1</sub>+''n''<sub>2</sub>+''n''<sub>3</sub> even. It reduces the computational work load for HF type calculations by a factor two, but is only sensible for high symmetry cases (such as sc, fcc or bcc cells). | {{TAG|EVENONLY}}=.TRUE. selects a subset of '''k'''-points with ''C''<sub>1</sub>=''C''<sub>2</sub>=''C''<sub>3</sub>=1, and ''n''<sub>1</sub>+''n''<sub>2</sub>+''n''<sub>3</sub> even. It reduces the computational work load for HF type calculations by a factor two, but is only sensible for high symmetry cases (such as sc, fcc or bcc cells). | ||
'''Mind''': [[ | '''Mind''': [[Downsampling_of_the_Hartree-Fock_operator#Caveat: when one should not use downsampling|there are circumstances under which '''NKRED''' and '''NKREDX''','''Y''','''Z''' should not be used!]] | ||
== Related Tags and Sections == | == Related Tags and Sections == | ||
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{{TAG|NKREDZ}}, | {{TAG|NKREDZ}}, | ||
{{TAG|ODDONLY}}, | {{TAG|ODDONLY}}, | ||
[[Hartree- | [[Downsampling of the Hartree-Fock operator|downsampling]] | ||
{{sc|EVENONLY|Examples|Examples that use this tag}} | {{sc|EVENONLY|Examples|Examples that use this tag}} | ||
Revision as of 20:21, 14 March 2022
EVENONLY = .TRUE. | .FALSE.
Default: EVENONLY = .FALSE.
Description: EVENONLY=.TRUE. selects a subset of k-points for the representation of the Fock exchange potential, with C1=C2=C3=1, and n1+n2+n3 even.
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 (N1×N2×N3) k-point set, {k}, for which the following holds
where b1,2,3 are the reciprocal lattice vectors of the primitive cell, and Ci is the integer grid reduction factor along reciprocal lattice direction bi.
EVENONLY=.TRUE. selects a subset of k-points with C1=C2=C3=1, and n1+n2+n3 even. It reduces the computational work load for HF type calculations by a factor two, but is only sensible for high symmetry cases (such as sc, fcc or bcc cells).
Mind: there are circumstances under which NKRED and NKREDX,Y,Z should not be used!
Related Tags and Sections
NKRED, NKREDX, NKREDY, NKREDZ, ODDONLY, downsampling