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 <[email protected]> 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 > <[email protected] <mailto:[email protected]>> 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 <[email protected] >> <mailto:[email protected]>> 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/>>_______________________________________________ >> Pw_forum mailing list >> [email protected] <mailto:[email protected]> >> http://pwscf.org/mailman/listinfo/pw_forum >> <http://pwscf.org/mailman/listinfo/pw_forum> > -- > > 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: [email protected] <mailto:[email protected]> > 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> > > > _______________________________________________ > Pw_forum mailing list > [email protected] <mailto:[email protected]> > http://pwscf.org/mailman/listinfo/pw_forum > <http://pwscf.org/mailman/listinfo/pw_forum> > > <plotband_gap.ps><plotgnu_gap.ps>_______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- 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: [email protected] 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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