[Pw_forum] Plotband.x

[Manu Hegde]

Hi Giovanni,

Thank you for your suggestions. I will increase the k-points and redo the
calculations.

Francesco, you are absolutely right. Aftet putting no_overlap=.true that
problem has gone.!

Thank you to both of you!

Manu
University of Waterloo


On Mon, Apr 18, 2016 at 4:15 AM, Francesco Pelizza <
francesco.pelizza at strath.ac.uk> wrote:

> Sorry to jump in this argument. I may be not of much help.
>
> For the question of overlapping bands or strange mixing of bands...In my
> experience, bands become easier to be plotted if when you run bands.x you
> add in the input file the flag: no_overlap= .true.
>
> That flag avoid eigenvalues overlapping and even plotband.x does a nice
> job.
>
> Francesco
> University of Strathclyde
>
>
>
>
> On 18/04/16 08:56, Giovanni Cantele wrote:
>
> bands crossing are spurious and they are due to the fact that, after
> running bands.x (or in the case you have not used it at all), the bands
> order might be incorrect. That means that the n-th band (that is, the band
> that at each k-point is
> plotted as n-th eigenvalue) might actually contain, at different k-points,
> energies belonging to different bands. In this case, if you not only plot
>  the points but also connect them with lines, you might see spurious
> connection lines between
> different bands. The way to cure this problem is to run bands.x before
> plotband.x, but with a sufficient number of k-points (if they are too
> distant bands.x might fail in following a band, that is, in assigning a
> given eigenvalue to a band).
>
> Giovanni
>
>
>
> On 18 Apr 2016, at 05:34, Manu Hegde < <mhegde at uwaterloo.ca>
> mhegde at uwaterloo.ca> wrote:
>
> Hi Giovanni,
>
> Thanks for your advice.
>
> I have calculated band structure for the zinc blende GaP lattice. When I
> plotted using gnuplot it looks okay (plotgnu_gap.ps).  But .ps format
> from the plotband.x (plotband_gap.ps) does not look properly and there
> some bands crossing. I am not sure why it is happening like this.  I have
> attached both the files.
>
> Regards,
> Manu
>
> Dr.Manu Hegde
> Postdoctoral Fellow
> Department of Chemistry
> University of Waterloo
>
> Waterloo, ON, N2L 3G1
>
>
> On Wed, Apr 6, 2016 at 6:26 AM, Giovanni Cantele <
> <giovanni.cantele at spin.cnr.it>giovanni.cantele at spin.cnr.it> wrote:
>
>> Quite likely, you did not calculate the band structure along a path in
>> the Brillouin zone, but used the output of the scf calculation (k-point
>> grid). After running pw.x with calculation=‘scf’ or calculation=‘relax’,
>> you need to rerun it with a new input file, calculation=‘bands’ and
>> K_POINTS card containing a suitable path of k-points. See also examples of
>> band structure calculation included in the QE-package.
>>
>> You can set Emin (Emax) to the value of the lowest (highest) eigenvalue),
>> unless you need to select some specific energy range.
>>
>> Giovanni
>>
>> PS Users of this forum are usually kindly requested to sign messages with
>> affiliation
>>
>> On 06 Apr 2016, at 05:25, Manu Hegde < <mhegde at uwaterloo.ca>
>> mhegde at uwaterloo.ca> wrote:
>>
>> Hello All,
>>
>> I was trying to plot band structure of PbTiO3, I could only see dots in
>> bands.ps file. I am not sure what is the reason for this. Is it due to
>> the wrong k-point selection?. I am also not sure about energy selection
>> along y-axis (Emax, Emin). I have attached bands.ps file please have a
>> look. Please help to overcome from this problem.
>>
>> Thanks and Regards
>>
>> Manu
>> <pbtio.bands.ps>_______________________________________________
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>>
>> --
>>
>> Giovanni Cantele, PhD
>> CNR-SPIN
>> c/o Dipartimento di Fisica
>> Universita' di Napoli "Federico II"
>> Complesso Universitario M. S. Angelo - Ed. 6
>> Via Cintia, I-80126, Napoli, Italy
>> e-mail: giovanni.cantele at spin.cnr.it
>> Phone: +39 081 676910
>> Skype contact: giocan74
>>
>> ResearcherID: http://www.researcherid.com/rid/A-1951-2009
>> Web page: http://people.na.infn.it/~cantele
>>
>>
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>
> <plotband_gap.ps><plotgnu_gap.ps>
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>
> --
>
> Giovanni Cantele, PhD
> CNR-SPIN
> c/o Dipartimento di Fisica
> Universita' di Napoli "Federico II"
> Complesso Universitario M. S. Angelo - Ed. 6
> Via Cintia, I-80126, Napoli, Italy
> e-mail: giovanni.cantele at spin.cnr.it
> Phone: +39 081 676910
> Skype contact: giocan74
>
> ResearcherID: http://www.researcherid.com/rid/A-1951-2009
> Web page: http://people.na.infn.it/~cantele
>
>
>
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