[DFTB-Plus-User] Problem with geometry optimization

[Pasan Henadeera]

Dear Bálint,
Thank you for the information. I appreciate the support.


Thank you

On Thu, 20 Jan 2022 at 17:22, Bálint Aradi <aradi at uni-bremen.de> wrote:

> Dear Pasan,
>
> your system is basically a metallic surface, therefore, it needs an
> electronic temperature to achieve proper convergence. Setting
>
>    Filling = MethfesselPaxton {
>      Temperature [K] = 1000
>     }
>
> should work.
>
> Two more remarks:
>
> * You could speed up the calculation somewhat by using the MPI-parallel
> version of the code, and the ELPA solver and processor groups (see the
> manual).
>
> * Your k-point sampling is unbiased. The cell is very large along a1 and
> a3, but short along a2, therefore, you it should be enough to use one
> k-point along b1 and b3, and 2 or 4 along b2.
>
> Best regards,
>
> Bálint
>
>
>
> On 16.01.22 13:12, Pasan Henadeera wrote:
> > Dear developers and users,
> >
> > I have been trying to use DFTB+ to optimise a structure made of Si
> > (consisting of around 750 atoms). However, even though I reduce the SCC
> > tolerance and increase the Max steps, I still am unable to figure out
> > how convergence can be obtained. Would it please be possible to give me
> > some guidance regarding this matter? I have attached the input and log
> > files as well. The optimization and Hamiltonian sections of the input
> > are as follows,
> >
> >
> > Driver = GeometryOptimization {
> > Optimizer = Rational {DiagLimit = 1.0e-2}
> > LatticeOpt = Yes
> > MaxSteps = 500
> > }
> >
> > Hamiltonian = DFTB {
> >    Scc = Yes
> >    SccTolerance = 0.2
> >    SlaterKosterFiles = Type2FileNames {
> >      Prefix = "../../../../slakos/wfc/"
> >      Separator = "-"
> >      Suffix = ".skf"
> >    }
> >      MaxAngularMomentum {
> >      Si = "d"
> >    }
> >    KPointsAndWeights = SupercellFolding {
> >      1 0 0
> >      0 2 0
> >      0 0 2
> >      0.5 0.5 0.5
> >    }
> > }
> >
> > ParserOptions {
> >    ParserVersion = 7
> > }
> >
> >
> >
> > I have only 16GB of memory, which is why I tried reducing the number of
> > k-points. However I got the same issue when using more k-points.
> >
> >
> > Thank you
> > --
> > Best regards
> > Pasan Henadeera
> >
> > _______________________________________________
> > DFTB-Plus-User mailing list
> > DFTB-Plus-User at mailman.zfn.uni-bremen.de
> >
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user
> >
>
>
> --
> 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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>


-- 
Best regards
Pasan Henadeera
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