[CP2K-user] [CP2K:21949] Re: Different eigenvalues from Hybrids + ADMM calculations in CP2K 2025.1 compared to 2024.1

[fabia...@gmail.com]

Hi Max,

I don't know where the difference comes from. But to get the band gap you 
need to switch off purification, so neither of those values are reliable. 
Change  ADMM_PURIFICATION_METHOD MO_DIAG to ADMM_PURIFICATION_METHOD NONE.
See, e.g. here: 
https://groups.google.com/g/cp2k/c/WAdLCCMk47A/m/fP0AeCaRBAAJ

Cheers,
Fabian
On Wednesday, 5 November 2025 at 10:54:38 UTC+1 Max Pierre wrote:

> Hello CP2K community,
>
> I have recently switched from cp2k-2024.1 to cp2k-2025.1 and initially got 
> some strange output. Running some test calculations using the same input 
> with both versions, I found that the energy eigenvalues are shifted, and 
> the HOMO - LUMO gap is much larger in 2025.1.
>
> - 2024.1:
> *
>       -0.15118136     -0.15058927     -0.15030345     -0.14919531
>       -0.14827092     -0.14449236     -0.14178774     -0.14087384
>       -0.14005256
>  Fermi Energy [eV] :   -3.811024
>   
>   Lowest Eigenvalues of the unoccupied subspace spin            1
>  -----------------------------------------------------
>  OT| Eigensolver reached convergence in 763 iterations
>        0.19181627
>   
>  HOMO - LUMO gap [eV] :    9.030610
>
>  ENERGY| Total FORCE_EVAL ( QS ) energy [a.u.]:           
>  -1322.383368758011557
> *
>
> - 2025.1:
> *
>       -0.25036349     -0.25011266     -0.24923456     -0.24855820
>       -0.24640841     -0.24154336     -0.23787275     -0.23769990
>       -0.23629481
>  Fermi Energy [eV] :   -6.429909
>   
>   Lowest Eigenvalues of the unoccupied subspace spin            1
>  -----------------------------------------------------
>  OT| Eigensolver reached convergence in 887 iterations
>        0.25231706
>   
>  HOMO - LUMO gap [eV] :   13.295805
>
>  ENERGY| Total FORCE_EVAL ( QS ) energy [hartree]         
>  -1322.383368757196422
> *
>
> Both calculations use PBE0 with ADMM pFIT3 and are started from a RESTART 
> file from a PBE calculations, the system is amorphous Polyethylene. The 
> 2024.1 HOMO-LUMO gap was pretty reasonable, the newer one is very high 
> compared with experimental values and previously reported hybrid functional 
> results. 
>
> I didn't find anyone else experiencing this issue, does anyone have any 
> idea what might be going on? 
>
> Thank you,
> Max
>
>

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