[DFTB-Plus-User] I could never get SCC converged for this structure

[Bálint Aradi]

Dear Achyut,

your input looks OK on the first glance. There is a fair chance, that 
your geometry is very unphysical, causing convergency problem. So first, 
I would recommend to check, if your geometry (including the periodic 
boundary conditions) is sound at all.

Otherwise, for systems which are hard to converge, sometimes using the 
Anderson mixer instead of the Broyden *might* give some advantages, so 
something like

   Mixer = Anderson {
     Generations = 15
     MixingParameter = 0.15
   }


Best regards,

Bálint

On 11/4/25 3:25 PM, Achyut Subedi wrote:
> Hello everyone,
> 
> I have been using DFTB for ab-initio molecular dynamic simulations for 
> different materials.
> Recently I tried to do some calculations for the structure attached.
> The problem is no matter what mixers I use or what parameters I use, the 
> SCC is never converged.
> 
> I tried setting the high electronic temperature and getting the initial 
> guess changes from it and then initializing the simulation at target 
> temperature as well. But the SCC converges for one step and then it 
> always rises or fluctuates.
> 
> Can anybody help me solve this problem by reproducing my problem? I 
> would be grateful.
> 
> Thank you for your time and consideration.
> 
> -- 
> Best Regards
> Er. Achyut Subedi
> Registered Mechanical Engineer
> (IOE, TU, Nepal)
> +977-9847703110
> 
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-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.uni-bremen.de/en/lmcqm/b-aradi

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