[Wien] Whether there would be energy difference between k point sampling via 2x2x3 & 3x2x2?

[shamik chakrabarti]

Dear Sir,

                I have to use these three numbers as I am trying to
initialize for HSE06 calculation...

On Fri, 25 Aug 2023 at 21:42, Peter Blaha <peter.blaha at tuwien.ac.at> wrote:

> Very basic solid state theory:
>
> k-space has NOTHING to do with atoms ....
>
> It is connected with the   reciprocal lattice  (what the hell is this ??)
>
> Anyway, if direct space (unit cell dimension) is large in one direction,
> reciprocal space is small. To sample k-space, you need many points when
> the reciprocal lattice vector is large (i.e. direct space is short) and
> vice versa.
>
> Obviously, if a and b axes of a lattice have equal length, you have to
> use the same number of points in these 2 directions in k-space.
> Otherwise, you should use a k-mesh ratio, which is inversely
> proportional to the unit cell length.
>
> And finally:   why are you choosing your k-mesh yourself by this
> dangerous method of specifying 3 numbers, if you have no idea what you
> are doing. Use the suggestions of WIEN2k_22 during initialization with a
> certain precision and the metal/nometal option.
>
> Am 25.08.2023 um 11:53 schrieb shamik chakrabarti:
> > Dear Sir,
> >
> >              Should I keep 3x2x2 for a structure having less atoms along
> > y & z -direction in comparison to x-direction?
> >
> > On Fri, 25 Aug 2023 at 20:46, Peter Blaha <peter.blaha at tuwien.ac.at
> > <mailto:peter.blaha at tuwien.ac.at>> wrote:
> >
> >     Did you do the calculations ? Then you know the answer.
> >
> >     All what we can say without details: One of the choices is for sure
> >     wrong.
> >
> >     Am 25.08.2023 um 07:15 schrieb shamik chakrabarti:
> >      > Dear Wien2k users,
> >      >
> >      >                           I have a basic question.
> >      > Whether there would be energy difference between k point sampling
> >     via
> >      > 2x2x3 & 3x2x2?
> >      >
> >      > Looking forward to your reply.
> >      >
> >      > witty regards,
> >      > --
> >      > Dr. Shamik Chakrabarti
> >      > Research Fellow
> >      > Department of Physics
> >      > Indian Institute of Technology Patna
> >      > Bihta-801103
> >      > Patna
> >      > Bihar, India
> >      >
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> >     --
> >
>  --------------------------------------------------------------------------
> >     Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> >     Phone: +43-1-58801-165300
> >     Email: peter.blaha at tuwien.ac.at <mailto:peter.blaha at tuwien.ac.at>
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> >
> >
> > --
> > Dr. Shamik Chakrabarti
> > Research Fellow
> > Department of Physics
> > Indian Institute of Technology Patna
> > Bihta-801103
> > Patna
> > Bihar, India
> >
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> --
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300
> Email: peter.blaha at tuwien.ac.at    WIEN2k: http://www.wien2k.at
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-- 
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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