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

[Nicholas Winner]

Vladimir,

(1) You're right that convergence (1e-6) is already reasonably good. For my 
testing, I already reran with 1e-6 EPS_SCF to get a final band gap. The 
issue is not that it is bad, but that the convergence behavior was 
unexpected. I am benchmarking in order to run medium-to-high throughput 
ADMM calculations, and I need to get a good handle on the ways in which 
calculations can stall in order to prepare for that.
(2) Reducing EPS_SCHWARZ to 1e-7 did assist a great deal in the 
convergence. Thank you. 
(3) Yes, running this on a Cray system. Is this a problem?

-Nick

On Friday, May 15, 2020 at 4:43:16 AM UTC-7, Vladimir Rybkin wrote:
>
> Dear Nick,
>
>
> 1) you convergence is not so bad already. At least, good enough for most 
> applications.
> 2) You Schwarz screening is rather large. Try 10-7 and smaller. Normally, 
> convergence is sensitive to the accuracy of Hartree-Fock exchange.
>
> are you by chance running it on a Cray system?
>
> Yours,
>
> Vladimir
>
> четверг, 14 мая 2020 г., 22:14:09 UTC+2 пользователь Nicholas Winner 
> написал:
>>
>> 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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