[DFTB-Plus-User] band structure SCC convergence

[R.Perez Garcia]

Dear dr. Penazzi,
Thank you very much for your kind answer.
I believe i follow the tutorial adecquately. I should copy the answer prof. Aradi gently send me a few seconds ago.
" If you use MaxSCCIterations = 1, the SCC won't converge, but you also
do not want it to converge, so it is fine.   Best regards,  Bálint"
So that problem is solved. However now I have dificulties to plot the  band_tot.dat if somebody could please explain the structure of the output would be fantastic.
Thank you very much for your attention.
Best regards: Rodrigo


On 11-07-12, Gabriele Penazzi  <gabriele.penazzi at bccms.uni-bremen.de> wrote:
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> On 07/11/2012 09:04 AM, R.Perez Garcia
>       wrote:
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> >         
> >             
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> > >                 Dear Prof. Aradi,
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> > >               
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> >               Dear DFTB+ especialists,
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> >               
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> > >                 
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> > >                   
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> > >                   
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> > >                   I am starting to use DBTB+ and I successfully did so
> > >                   until now. 
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> > >                   I can not calculate the band structure due to a
> > >                   convergence problem.
> > > 
> > >                   I did follow your tutorial, and after SCC convergence
> > >                   (21iterations) and satisfactorily calculate the DOS,
> > >                   the BandStructure calculation crashes.
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> > >                   
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> > >                   I put the necessary files, charges.bin and geom.gen,
> > >                   in a new directory  together with the dftb_in.hsd
> > >                   (with all the small changes suggested by you, I think
> > >                   ) but it can not converged.[cut]
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> > >               
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>     Hi Rodrigo,
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>     from your input file and output error it looks like you're trying to
>     solve the SCC cycle again. This is wrong, you must first calculate
>     the charge density with a k-point sampling suitable for that, and
>     then import the charge in the band structure calculation WITHOUT
>     solving the scc cycle again. Otherwise the code will try to  solve
>     it using as a k-point sampling the k lines you specified, that's why
>     it doesn't converge.
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>     Check the online example:
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>     http://www.dftb-plus.info/fileadmin/DFTB-Plus/public/recipes/html/basics/bandstruct.html
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>     In the section "Calculating the band structure" in the input file
>     there's a flag "ReadInitialCharges = Yes"
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>     Copy again your charges from the converged calculation and use this
>     flag (which gives instruction to the code not to calculate the
>     charge again), and probably your problem will be gone.
> 
>     
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>     Gabriele
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> -- 
> Dr. Gabriele Penazzi
> BCCMS - University of Bremen
> 
> http://www.bccms.uni-bremen.de/
> http://sites.google.com/site/gabrielepenazzi/
> 
> phone: +49 (0) 421 218 62337
> fax: +49 (0) 421 218 62770
> 
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