Keywords in KPOINTS section

[Lucas Bandeira]

Dear cp2k community,

I am trying to understand some of the keywords in the KPOINTS section. They are the WAVEFUNCTIONS, FULL_GRID, and SYMMETRY keywords. 

If I set FULL_GRID TRUE, will integrals also be evaluated outside the Irreducible Brillouin Zone? Or this keyword has nothing to do with it. When should I set it to TRUE or FALSE?

About the WAVEFUNCTION keyword, when should I set it to REAL or to COMPLEX? In the cp2k exercise to compute the band structure of graphene, it was set to REAL, but I had some problems using it for metallic systems, so I swapped it to COMPLEX.

About the SYMMETRY keyword, I am optimizing the geometry of a cubic metallic bulk. So it is OK to set it to TRUE. But, when working with slabs, I should set it to FALSE, because the vacuum layer removes the symmetry of the system. Is that right? Could somebody give me other examples of when I should set it to TRUE or FALSE?

Yours sincerely, 

Lucas Bandeira

[hut...@chem.uzh.ch]

Hi

some additional information on the kpoints keywords:

FULL_GRID T/F : If false uses time reversal to reduce number of k-points (default)
Symmetry T/F : Reduces number of kpoints according to symmetry operations (this is
currently not availbale in CP2k)
Wavefunction Real/Complex : orbitals in kpoint calculations are by default complex.
For some specific choices of kpoints (gamma point, zone boarders)
wfn can be chosen to be real.

regards

Juerg Hutter
--------------------------------------------------------------
Juerg Hutter Phone : ++41 44 635 4491
Institut für Chemie C FAX : ++41 44 635 6838
Universität Zürich E-mail: hut...@chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp...@googlegroups.com wrote: -----
To: cp...@googlegroups.com
From: "Lucas Bandeira"
Sent by: cp...@googlegroups.com
Date: 05/16/2021 07:09PM
Subject: [CP2K:15388] Keywords in KPOINTS section

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[sumit agrawal]

Hii,

I am also confused with this section. Can anybody explain what the below input will do.  What is the meaning of SCHEME, FULL_GRID. Actually I want to calculate the lattice constant for an argon unit cell. 

&KPOINTS

   SCHEME  MONKHORST-PACK  8  8  8
   FULL_GRID  .TRUE.

&END KPOINTS

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