> On 05 Jul 2015, at 18:29, Gul Rahman <gulrah...@qau.edu.pk> wrote: > > Dear All, > I am doing some test calculations on 2D Sn and comparing QE with SIESTA. Both > QE and SIESTA almost give the same results (DOS, lattice constnat, charge,,). > However, I have problem with the band structure. I want to plot the band > structure in > 0.0,0.0 0.0 to 0.33,0.330.00 to 0.5,0.0,0.0. > I either write a python code or jut do by hand to put the number of points in > the input file for the band structure calculation. > _POINTS crystal > 29 > 0.00000 0.00000 0.00000 1.0000 > 0.03000 0.03000 0.00000 1.0000 > 0.06000 0.06000 0.00000 1.0000 > 0.09000 0.09000 0.00000 1.0000 > 0.12000 0.12000 0.00000 1.0000 > 0.15000 0.15000 0.00000 1.0000 > 0.18000 0.18000 0.00000 1.0000 > 0.21000 0.21000 0.00000 1.0000 > 0.24000 0.24000 0.00000 1.0000 > 0.27000 0.27000 0.00000 1.0000 > 0.30000 0.30000 0.00000 1.0000 > 0.33000 0.33000 0.00000 1.0000 > 0.34000 0.31060 0.00000 1.0000 > 0.35000 0.29120 0.00000 1.0000 > 0.36000 0.27180 0.00000 1.0000 > 0.37000 0.25240 0.00000 1.0000 > 0.38000 0.23300 0.00000 1.0000 > 0.39000 0.21360 0.00000 1.0000 > 0.40000 0.19420 0.00000 1.0000 > 0.41000 0.17480 0.00000 1.0000 > 0.42000 0.15540 0.00000 1.0000 > 0.43000 0.13600 0.00000 1.0000 > 0.44000 0.11660 0.00000 1.0000 > 0.45000 0.09720 0.00000 1.0000 > 0.46000 0.07780 0.00000 1.0000 > 0.47000 0.05840 0.00000 1.0000 > 0.48000 0.03900 0.00000 1.0000 > 0.49000 0.01960 0.00000 1.0000 > 0.50000 0.00020 0.00000 1.0000 > > when I used it, I always see crossing points in the band structure. Pls, see > the attached file and you can see crossing points not only around Dirac > point, but also above that. > Could you plz let me know why I am facing this problem whenever I try the > band structure of any material and I will have these crossing lines.
Are you referring to the crossings around -1.5 and + 1.5 eV? These are just spurious, and are due to the fact that because consecutive points are connected in the plot, if the ordering of the bands is not the proper one, a point in a lower bands is connected not to the next point in the same band but to a point in a higher band. Plotting the band structure only with points or calculating the band structure with a larger number of k-points solves the problem, Other crossings (e.g. around 4 eV) are instead the results of the calculation, so if you do not expect them it means that your input files do contain some error (e.g. k-points coordinates). > > Is there any option in QE for calculating these points by just giving the > high symmetry points in the input for band structure calculations. Yes, with the latest version. You can specify a k-point path as follows: K_POINTS { crystal_b } 5 gG 50 M 50 X 50 R 50 gG 1 which corresponds to 5-1=4 lines in the Brillouin zone of a simple cubic lattice, that s, Gamma-M, M-X, X-R, R-Gamma, each sampled with 50 points. The point labels that are recognised are shown in detail in espresso-5.2.0/Doc/brillouin_zones.pdf Giovanni > Thanks, > Gul > > -- > > Dr. Gul Rahman > Assistant Professor, > Department of Physics, > Quaid-i-Azam University, > Islamabad, Pakistan > http://www.qau.edu.pk/profile.php?id=818020 > <http://www.qau.edu.pk/profile.php?id=818020><bands.ps>_______________________________________________ > Pw_forum mailing list > Pw_forum@pwscf.org > 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: giovanni.cant...@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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