[Pw_forum] Kponts generation from kpoint.x

[Vo, Trinh (388C)]

Hi Paol and Gabriele,

Thank you very much for reply.

Yes, I need kpoints for entire BZ.  Yes, I used that option (kpoint.x) to
print out all kpoints. I then found that a number of kpoints from pw.x did
not in the list of kpoints generated by kpoint.x, so I was confused.  I have
just made further checks, I saw that they are actually equivalent within a
reciprocal vector.  Thus it is fine now.  :-).

Thank you 


On 2/4/10 12:02 AM, "Gabriele Sclauzero" <sclauzer at sissa.it> wrote:

> 
> 
> vtmtrinh at caltech.edu wrote:
>> Dear PWSCF Users,
>> 
>> I also checked prevoius discussions in PWSCF forum.  pw.x also takes into
>> consideration of the crystal symmetry, while kpoint.x uses lattice
>> symmetry.  (My studied system is body-cntered tetragonal cell). It seems
>> that I could not use the kpoints list given by kpoint.x.   If I would like
> 
> You got the point!
> 
>> to obtain a whole list of kpoints (consistent with those generated by
>> pw.x), how could I do so?
> 
> I'm not sure that your request is totally clear to me. If you want the full
> list of 
> k-points, without any symmetry reduction, you can use kpoints.x: it has an
> option which 
> prints on output the full list, together with an index which tells you if
> there is in the 
> list another k-point which is equivalent by symmetry.
> I think you could even generate the mesh "by hand" in crystal coordinates: it
> is a 
> regularly spaced grid in a three dimensional cube, possibly shifted from the
> origin.
> Give a look inside PW/kpoint_grid.f90:
> 
>    do i=1,nk1
>       do j=1,nk2
>          do k=1,nk3
>             !  this is nothing but consecutive ordering
>             n = (k-1) + (j-1)*nk3 + (i-1)*nk2*nk3 + 1
>             !  xkg are the components of the complete grid in crystal axis
>             xkg(1,n) = DBLE(i-1)/nk1 + DBLE(k1)/2/nk1
>             xkg(2,n) = DBLE(j-1)/nk2 + DBLE(k2)/2/nk2
>             xkg(3,n) = DBLE(k-1)/nk3 + DBLE(k3)/2/nk3
>          end do
>       end do
>    end do
> 
> However maybe there is no need to do this if you simply want to run a nscf
> calculation on 
> a full 3D grid of k-point; try with
> 
> nosym=.TRUE.
> noinv=.TRUE.
> 
> It should disable any symmetry reduction in the generation of the k-point list
> (but also 
> symmetrization of charge).
> 
> 
> 
> HTH
> 
> GS
> 
> 
> 
>> 
>> Thank you,
>> 
>> Trinh
>> 
>>> Dear Pwscf,
>>> 
>>> I run a nscf calculation with k-point grid of 12x12x12 (automatic).  From
>>> the output of pw.x, I saw 163 kpoints were generated and computed.  Since
>>> I would like to get the whole 3D-band structure, I run kpoint.x to get
>>> other kpoints.  A number of kpoints generated by pw.x (for the nscf
>>> calcultion) could be found te coincide with those generated by kpoint.x.
>>> However, there many kpoints generated by pw.x could not found in the
>>> output of kpoint.x.  I am not sure about the reason why there is the
>>> difference here: Is it due to reverse symmetry or something else?   I
>>> appreciate very much if you could tell me why.
>>> 
>>> Best,
>>> 
>>> Trinh Vo
>>> 
>>> JPL/CalTech
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://www.democritos.it/mailman/listinfo/pw_forum
>>> 
>> 
>> 
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