[SIESTA-L] 回复: discrepancy in kpoints generation for band structure calculation

[Zhang Aihua]

Dear Alberto,

Thanks for the explanation! I did perform the two calculations in two runs.

Best regards

Aihua

-------- 原始邮件 --------
主题：Re: [SIESTA-L] discrepancy in kpoints generation for band structure
calculation
发件人：Alberto Garcia
收件人：siesta-l@uam.es
抄送：

Dear Aihua,

During a cell-relaxation run, at each step Siesta will use the sampling instructions (i.e. MP 8x8x8) and the current lattice-vectors to compute the k-point absolute coordinates in bohr^-1. So the k-point coordinates will indeed change, but in this case not the sampling itself. On the other hand, if you were to specify the k-point quality through the kgrid-cutoff fdf parameter, it is possible that for a certain geometry change the number of k-points changes.

My point was about possible inconsistencies arising if you were to perform a cell relaxation followed by a band-structure calculation in the same run. Since the
k-point coordinates for the band-structure calculation are computed at the beginning of the run, they would be appropriate for the initial cell, not the final one. This can be considered a bug or a feature...

Alberto

On 19 May 2016, at 03:13, Zhang Aihua wrote:

> Dear Alberto,
>
> Thanks for the information. I will download and use the latest version.
>
> I don't quite get your advice as not to perform a band structure calculation at the end of a
>
> cell relaxation. I did the band structure calculation in a separate run after cell relaxation has
>
> converged. Since there is only a small fraction of change in one cell dimension, I have used
>
> a fixed k-points sampling throughout these calculations. Do you mean that Siesta does a k-points
>
> re-sampling after every cell relaxation step?
>
> Best regards
>
> Aihua
>
>
> > -----Original Messages-----
> > From: "Alberto Garcia"
> > Sent Time: Wednesday, May 18, 2016
> > To: siesta-l@uam.es
> > Cc:
> > Subject: Re: [SIESTA-L] discrepancy in kpoints generation for band struct ure calculation
> >
> > Hi Aihua,
> >
> > This problem is corrected in the latest version (4.0-b2) in