[CP2K-user] [CP2K:19108] Re: diamond with TC-LRC + ADMM very slow

[Martin Konôpka]

Dear Frederick,

Thanks. You are right, there were too many integrals to do on the fly. I
checked some of my previous calculations with the PBE0 TC-RLC + ADMM
techniques (a TiO2 rutile system) and I see there were zero integrals to do
on the fly in those jobs (on the same machine). That's a pretty difference.
Unfortunatelly, with diamond even switching to cpFIT3 and releasing
EPS_DEFAULT to 10^{-11} (by three orders of magnitude) did not help. After
almost three hours even the 1st electronic iteration was not over (or at
least no writing produced) and I stopped the job. A much more radical
truncation and/or optimisation of the basis sets would be needed. At least
for now, I am going to abandon PBE0 and use just PBE for this diamond
system. And it looks that for PBE, plane waves with ultrasoft
pseudopotentials are a much faster approach for this (rather dense)
material. (I did a quick test today with the CPMD code using a 35 Ry PW
cutoff.)

Best wishes
Martin.

št 13. 7. 2023 o 13:17 'Frederick Stein' via cp2k <cp2k at googlegroups.com>
napísal(a):

> Dear Martin,
>
> From your PBE0 output file, I see that most integrals are calculated on
> the fly indicating that your machine does not have enough memory to store
> all integrals. This increases the compute time significantly. What you
> could try is to
> 1) replace the pFIT3 with the cpFIT3 basis set to reduce the number of
> contracted basis functions
> 2) increase the EPS_DEFAULT parameter to reduce the number of matrix
> elements and number of integrals to calculate (only if your accuracy
> demands are still met)
>
> HTH,
> Frederick
> Martin Konôpka schrieb am Donnerstag, 13. Juli 2023 um 11:49:05 UTC+2:
>
>> Dear CP2K experts,
>>
>> I tried to use PBE0 functional with the TC-LRC + ADMM technique to
>> calculate bulk diamond in a (110)-oriented cell. First however I used PBE
>> (with the same grids etc) to produce a good initial guess for
>> wavefunctions. The PBE calculation on 14 cores took about 249 sec per
>> electronic iteration. Then I started PBE0 on 18 cores. It took 9909 sec
>> (the 2nd iteration), which is unexpectedly long time. You can see attached
>> my I/O files. BTW, concurrently with the PBE calculation, another
>> calculation was running on the remaining 4 cores of the machine. Without
>> that additional load and using all 18 cores, the time would drop to 194 sec
>> only (PBE).
>>
>> I have a some experience with using the TC-LRC + ADMM technique for TiO2
>> systems and also for some organic molecules. In those cases PBE0 was always
>> just about 2-3 times slower than PBE. Now I see the enormous ratio and do
>> not understand the reason.
>>
>> Also, I was surprised by huge memory consumption by the PBE0 calculation:
>> Over 200 GB in total. Still, it fit in the available memory (256 GB DDR4)
>> and the machine remained perfectly responsive. Isn't there some problem
>> with the basis sets that I used for carbon?
>>
>> The cp2k version that I used was 9.1, the "factory" one provided by the
>> package manager on ubuntu 22.04. I am using also Intel MKL installed
>> through the package manager. I launched the calculation in a screen session
>> by the command
>>      mpirun -np 18 cp2k.popt -i cp2k.inp -o cp2k.out
>> The machine is a single-socket one with hyperthreading off.
>>
>> Thanks for your opinions and for your work on bulding the CP2K code.
>>
>> Sincerely
>> Martin Konôpka.
>>
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