[CP2K-user] [CP2K:20775] Re: SCF Convergence Issues with OT and Diagonalization for CZTS System (Vacuum, Sulfur Layer, and Hydrogen Passivation

[Marcella Iannuzzi]

Hi ..

Maybe it simply needs to run for more iterations to converge.
With the information you provide it is hard to guess.
Is the electronic structure calculation of the bulk working fine?
Can you reproduce with your settings (BS, PP, XC etc) the known bulk 
properties?

Regards
Marcella



On Wednesday, October 16, 2024 at 7:40:32 PM UTC+2 lheid... at gmail.com wrote:

> Hello CP2K community,
>
> I am running molecular dynamics (MD) simulations on a *Cu2ZnSnS4 (CZTS)* 
> system using *DFT* in CP2K. Below is a detailed description of my system 
> and the modifications I applied, followed by the SCF convergence issue I am 
> facing.
>
> Cu2ZnSnS4 (CZTS) system modeled in a periodic box.
> Unit cell dimensions: 10.8 × 10.8 × 10.8 Å.
> The goal is to study surface interactions and electronic properties with a 
> vacuum layer.
>
> A 20 Å vacuum layer was added in the Z direction to simulate surface 
> effects: 10.8 × 10.8 × 30.8 Å
>
> A layer of sulfur (S) atoms was added to the surface to stabilize the 
> system and account for surface states.
>
> I attempted hydrogen passivation by capping the dangling bonds with H 
> atoms to further stabilize the surface.
> I tried running the SCF loop with and without hydrogen passivation, but 
> both cases failed to converge.
>
> SCF Settings and Methods Tried:
> *Orbital Transformation (OT):*
> MINIMIZER: DIIS
> PRECONDITIONER: FULL_SINGLE_INVERSE
> ENERGY_GAP: 0.001
> N_HISTORY_VEC: 7
> *Diagonalization:*
> I disabled the OT section and enabled diagonalization as a fallback 
> method, but the SCF still did not converge. ( I tried different parameters 
> setting)
> SCF Parameters:
> SCF_GUESS: ATOMIC
> EPS_SCF: 1.0E-6
> MAX_SCF: 100
>
> *The SCF loop exits after a few minutes, failing to converge under both OT 
> and diagonalization methods.*
> Are there specific SCF settings or preconditioners that can improve 
> convergence for systems with large vacuum gaps?
> Are there alternative strategies for handling surfaces and vacuum layers 
> that could make the system more stable for electronic structure 
> calculations?
> Has anyone successfully applied hydrogen passivation to stabilize surfaces 
> and improve SCF convergence in CP2K?
>
> Any suggestions or advice would be greatly appreciated!
>
> Thank you for your help and support.
>
>
>

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