[CP2K-user] [CP2K:13305] SCF Convergence stuck with ADMM HF?

[hut... at chem.uzh.ch]

Hi

this behaviour usually points towards a lack of overall accuracy
in the calculation. In your case, I would decrease

EPS_DEFAULT   and  EPS_SCHWARZ

You might also want not to screen HFX on initial P when you start
an SCF from an inaccurate initial guess. Screened away integrals 
are lost for the whole SCF procedure.

regards

Juerg Hutter

--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "Nicholas Winner" 
Sent by: cp... at googlegroups.com
Date: 05/14/2020 10:14PM
Subject: [CP2K:13305] SCF Convergence stuck with ADMM HF?

Hello all,

I have tried to perform static PBE0 calculation of diamond using the ADMM. I have done many of this type of calculation before, but not for this system. I have an issue where the reported "convergence" in the SCF loop is unchanged for many steps. I initially tried using the DIIS minimizer and OT method, but switched to 2PNT CG search to try to improve convergence. This helped a tiny amount (convergence got lower, but still stuck). 

I'm unclear as to what the problem is. I have attached my input and output files. Note I stopped this calculation prematurely.

Drawing your attention to the first inner SCF loop of the output file, I can see that SCF step 19-50 all report the same convergence of (0.00000035) with no change. What's more, the "total energy" in that loop is listed as -3903.4843979582 for all steps after 31. So it seems that the energy is extremely well converged... better than the EPS_SCF 1e-7 that I listed in the input file.

I'd like to know if there's any reason why this would be having such a hard time converging; diamond is a large band gap material and should have very good convergence with OT, especially with CG. Also, am I misunderstanding hte numbers reported by the SCF steps? It seems to me the total energy is very well converged to within 1e-9 the end of the first SCF loop, but convergence is listed as .00000035.

Any help would be appreciated.

Best,
Nick  
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