[DFTB-Plus-User] Defect + magnetism

[Ben Hourahine]

Hello Toufik,

Did the system possibly relax to an unpolarized state (as would be
possible with RelaxTotalSpin=Yes)? Check the detailed.out for the number
of up and down electrons, but also try removing that option (but leaving
UnpairedElectrons = 1).


Regards


Ben


On 10/03/2020 10:18, toufik esssakhri via DFTB-Plus-User wrote:
> Thank you very much,
> In fact, I am comparing my results with DFT calculations, from DFT
> dos_up and dos_down
> are different. As you said, to break spin symmetry I set
> RelaxTotalSpin to yes. Present atoms
> are not magnetic. The origin of magnetism is the defect. Thus Iam not
> using SpinPerAtom
> initialisation. Here is the spin polarisation block I am using:
>
>   SpinPolarisation = Colinear {
>     UnpairedElectrons = 1
>     RelaxTotalSpin = Yes
>   }
>   SpinConstants = {
>     ShellResolvedSpin = Yes
>     C = { -0.0306  -0.0251  -0.0251  -0.0255 }
>     F = { -0.0370  -0.0312  -0.0312  -0.0299 }
>   }
> I wonder if I am missing something
>
> Best Regards
> *
> *
> *
> *
> *De :* DFTB-Plus-User
> <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> de la part de
> Bálint Aradi via DFTB-Plus-User <dftb-plus-user at mailman.zfn.uni-bremen.de>
> *Envoyé :* mardi 10 mars 2020 10:59
> *À :* dftb-plus-user at mailman.zfn.uni-bremen.de
> <dftb-plus-user at mailman.zfn.uni-bremen.de>
> *Cc :* Bálint Aradi <aradi at uni-bremen.de>
> *Objet :* Re: [DFTB-Plus-User] Defect + magnetism
>  
> Dear Toufik,
>
> On 3/9/20 9:22 PM, toufik esssakhri via DFTB-Plus-User wrote:
> > Thank for your response,
> > Attached the density of states, we can see the dos_up  = dos_down
> > from the band.out file  we get the defect levels :
>
> To me, the band.out snippet and the dos seems to me consistent. You have
> two peaks in the DOS: around -8.3 and -8.6, the one at -8.6 is roughly
> twice as big as the one at -8.3. You can decrease the broading as a
> command line argument to dp_dos, but to me, it seems to be OK as it is.
>
> Now, whether spin-up and spin down must differ is a different question.
> It depends on your system. You probably want to set RelaxTotalSpin = Yes
> so that you have one common Fermi-level for both spin channels. And it
> may be necessary to start from a spin-polarized initial guess (see
> InitialSpins) to break the spin symmtetry.
>
>   Best regards,
>
>   Bálint
>
>
> -- 
> Dr. Bálint Aradi
> Bremen Center for Computational Materials Science, University of Bremen
> http://www.bccms.uni-bremen.de/cms/people/b-aradi/
>
>
>
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-- 
        Dr.  B.  Hourahine,  Senior  lecturer
            SUPA, Department  of  Physics,
             University  of  Strathclyde,
              John  Anderson  Building,
          107 Rottenrow, Glasgow G4 0NG, UK.                    
  +44 141 548 2325, benjamin.hourahine at strath.ac.uk

The  Department is  a partner  in SUPA,  the Scottish
            Universities Physics Alliance

The University  of Strathclyde  is a  charitable body,
       registered in Scotland, number SC015263

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