[Pw_forum] Plotband.x

[Giovanni Cantele]

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> 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 <http://plotgnu_gap.ps/>).  But .ps format from the plotband.x (plotband_gap.ps <http://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 <mailto: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 <mailto:mhegde at uwaterloo.ca>> wrote:
>> 
>> Hello All,
>> 
>> I was trying to plot band structure of PbTiO3, I could only see dots in bands.ps <http://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 <http://bands.ps/> file please have a look. Please help to overcome from this problem.
>> 
>> Thanks and Regards
>> 
>> Manu
>> <pbtio.bands.ps <http://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 <mailto:giovanni.cantele at spin.cnr.it>
> Phone: +39 081 676910 <tel:%2B39%20081%20676910>
> Skype contact: giocan74
> 
> ResearcherID: http://www.researcherid.com/rid/A-1951-2009 <http://www.researcherid.com/rid/A-1951-2009>
> Web page: http://people.na.infn.it/~cantele <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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