That was indeed the issue! For some reason in cp2k-2024.1 the ADMM band gaps were very close to the normal PBE0 ones even with purification switched on, so I hadn't noticed that anything was off before switching to 2025.1. I guess I was just lucky before that using the wrong purification setting wasn't causing any big issues for me in 2024.1.<br /><div><br /></div><div>Thank you for the help!</div><div>Max</div><div><br /></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Wednesday, 5 November 2025 at 14:12:28 UTC+1 fabia...@gmail.com wrote:<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>Hi Max,</div><div><br></div><div>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 <span><span>ADMM_PURIFICATION_METHOD</span></span><em><span><span></span></span></em>
<span><span>MO_DIAG to</span></span>
<span><span>ADMM_PURIFICATION_METHOD</span></span> NONE.<br>See, e.g. here: <a href="https://groups.google.com/g/cp2k/c/WAdLCCMk47A/m/fP0AeCaRBAAJ" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://groups.google.com/g/cp2k/c/WAdLCCMk47A/m/fP0AeCaRBAAJ&source=gmail&ust=1762500736581000&usg=AOvVaw0jBhx_8w4eMrKqNFXqXokx">https://groups.google.com/g/cp2k/c/WAdLCCMk47A/m/fP0AeCaRBAAJ</a></div><div><br></div><div>Cheers,</div><div>Fabian</div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Wednesday, 5 November 2025 at 10:54:38 UTC+1 Max Pierre wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hello CP2K community,<div><br></div><div>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.</div><div><br></div><div>- 2024.1:</div><div>*</div><div> -0.15118136 -0.15058927 -0.15030345 -0.14919531<br> -0.14827092 -0.14449236 -0.14178774 -0.14087384<br> -0.14005256<br> Fermi Energy [eV] : -3.811024<br> <br> Lowest Eigenvalues of the unoccupied subspace spin 1<br> -----------------------------------------------------<br> OT| Eigensolver reached convergence in 763 iterations<br> 0.19181627<br> <br> HOMO - LUMO gap [eV] : 9.030610<br><br> ENERGY| Total FORCE_EVAL ( QS ) energy [a.u.]: -1322.383368758011557</div><div>*</div><div><br></div><div>- 2025.1:</div><div>*</div><div> -0.25036349 -0.25011266 -0.24923456 -0.24855820<br> -0.24640841 -0.24154336 -0.23787275 -0.23769990<br> -0.23629481<br> Fermi Energy [eV] : -6.429909<br> <br> Lowest Eigenvalues of the unoccupied subspace spin 1<br> -----------------------------------------------------<br> OT| Eigensolver reached convergence in 887 iterations<br> 0.25231706<br> <br> HOMO - LUMO gap [eV] : 13.295805<br><br> ENERGY| Total FORCE_EVAL ( QS ) energy [hartree] -1322.383368757196422</div><div>*</div><div><br></div><div>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. </div><div><br></div><div>I didn't find anyone else experiencing this issue, does anyone have any idea what might be going on? </div><div><br></div><div>Thank you,</div><div>Max</div><div><br></div></blockquote></div></blockquote></div>
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