[Pw_forum] NaN error in plotbandband.x - error in k-path?
Giovanni Cantele
giovanni.cantele at spin.cnr.it
Tue Mar 1 16:49:22 CET 2016
The error comes from the calculation=‘bands’ run. Indeed, you just specified the extrema of high symmetry lines (G, R, X, M) in the Brillouin zone,
but you used as units “crystal” instead of “crystal_b”. The latter keyword tells pw.x to build a path of (in your case) 20 points along each line, whereas
the former just instructs pw.x to calculate the eigenvalues at the specified k-points. If you look at the header of bands.dat you find nks=4, that is, the bands
have been calculated only at G, R, X, M and no additional k-points have been considered.
This being said. when plotband.x reads bands.dat, at some point there is the following code:
! A big jump in dxmod is a sign that the point k(:,n) and k(:,n-1)
! are quite distant and belong to two different lines. We put them on
! the same point in the graph
!
kx(n)=kx(n-1)
So, because no additional points were added between each pair, all the computed k-points where put on the same point of the plot, that is, kx(n)=0, for n=1,2,3,4.
At the stage were plotband.x writes the ps file:
DO i=1,nbnd
IF (is_in_range(i)) WRITE (1,'(2(f8.3,1x)," dot")' ) &
kx(n)*xdim/kx(nks), (e(i,n)-emin)*ydim/(emax-emin)
ENDDO
so, you see that the division by kx(nks)=0 is undefined, which produces the NaNs.
Not related to the error, consider that ecutwfc=24 might be too low and insufficient to get converged results, for the kind of pseudo potentials you are using.
Giovanni
> On 01 Mar 2016, at 16:28, Christoph Wolf(신소재공학과) <chwolf at postech.ac.kr> wrote:
>
> Dear All!
>
> I am trying to calculate the band structure of a (tiny) simple cubic unit cell containing 12 atoms of 5 species. I imported to structure from a CIF file via VESTA.
>
> 1) First I am running an &scf and it seems to converge.
> 2) Then I am running &bands and it finishes fine without errors
> 3) Then I am running bands.x and generate an output file which seems fine, no NaN there
> 4) When I use plotband.x (interactive mode) the created ps file contains NaN and I don’t understand where they come from
>
> The output of the bands looks something like this:
>
> &plot nbnd= 24, nks= 4 /
> 0.000000 0.000000 0.000000
> -18.411 -12.728 -12.287 -11.961 -10.967 -7.359 -7.181 -5.332 -4.940 -3.029
> -3.013 -2.097 -2.045 -1.873 -0.112 -0.047 0.005 0.136 0.448 0.470
> 5.704 7.022 7.067 7.347
>
> But then the ps file contains lots of:
>
> NaN 0.000 NaN 284.530 riga
> NaN 11.303 dot
> NaN 51.728 dot
> NaN 54.865 dot
>
>
> My input files are as follows (maybe someone can spot the error). Version is 5.0.2 on ubuntu
>
> Any help is greatly appreciated!
>
> Yours,
> Chris
>
>
> &control
> calculation='scf'
> restart_mode='from_scratch',
> pseudo_dir = '/usr/share/espresso/pseudo/',
> outdir='/usr/share/doc/quantum-espresso/examples/MAPbBr3/tmp/'
> prefix='mapbbr3'
> /
> &system
> ibrav=1, a=5.9200000763, nat=12, ntyp=5, ecutwfc = 24.0, nbnd = 24
> /
> &electrons
> /
> ATOMIC_SPECIES
> C 12.01 C.pbe-hgh.UPF
> N 14.01 N.pbe-hgh.UPF
> H 1 H.pbe-hgh.UPF
> Pb 207.19 Pb.pbe-hgh.UPF
> Br 79.9 Br.pbe-hgh.UPF
> ATOMIC_POSITIONS
> C 0.896270000 0.999980000 0.988510000
> N 0.142130000 0.999830000 0.032690000
> H 0.866960000 0.999760000 0.805200000
> H 0.822470000 0.152470000 0.064660000
> H 0.822200000 0.847840000 0.065070000
> H 0.221280000 0.142420000 0.965660000
> H 0.221080000 0.856980000 0.965950000
> H 0.180460000 0.999970000 0.205370000
> Pb 0.475340000 0.500000000 0.477920000
> Br 0.428780000 0.499880000 0.972690000
> Br 0.433480000 0.000020000 0.512850000
> Br 0.967550000 0.500170000 0.439210000
> K_POINTS (automatic)
> 10 10 10 0 0 0
>
>
> &control
> calculation='bands'
> pseudo_dir = '/usr/share/espresso/pseudo/',
> outdir='/usr/share/doc/quantum-espresso/examples/MAPbBr3/tmp/'
> prefix='mapbbr3'
> /
> &system
> ibrav=1, a=5.9200000763, nat=12, ntyp=5, ecutwfc = 24.0, nbnd = 24
> /
> &electrons
> /
> ATOMIC_SPECIES
> C 12.01 C.pbe-hgh.UPF
> N 14.01 N.pbe-hgh.UPF
> H 1 H.pbe-hgh.UPF
> Pb 207.19 Pb.pbe-hgh.UPF
> Br 79.9 Br.pbe-hgh.UPF
> ATOMIC_POSITIONS
> C 0.896270000 0.999980000 0.988510000
> N 0.142130000 0.999830000 0.032690000
> H 0.866960000 0.999760000 0.805200000
> H 0.822470000 0.152470000 0.064660000
> H 0.822200000 0.847840000 0.065070000
> H 0.221280000 0.142420000 0.965660000
> H 0.221080000 0.856980000 0.965950000
> H 0.180460000 0.999970000 0.205370000
> Pb 0.475340000 0.500000000 0.477920000
> Br 0.428780000 0.499880000 0.972690000
> Br 0.433480000 0.000020000 0.512850000
> Br 0.967550000 0.500170000 0.439210000
> K_POINTS |(crystal)
> 4
> 0.0 0.0 0.0 20 !G
> 0.5 0.5 0.5 20 !R
> 0.0 0.5 0.0 20 !X
> 0.5 0.5 0.0 20 !M
>
>
> &bands
> outdir='/usr/share/doc/quantum-espresso/examples/MAPbBr3/tmp/'
> prefix='mapbbr3'
> filband='bands.dat'
> /
>
>
>
>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org>
> 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: 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20160301/0f707c18/attachment.html>
More information about the users
mailing list