[CP2K-user] [CP2K:18549] Re: Cutoff convergence for SCAN functional

[Rajorshi Chattopadhyay]

Hello Fabian,

I thank you for your reply.

When I do cutoff convergence test with r2SCAN, I get the following energy
values till 1500Ry (REL_CUTOFF:60):

Cutoff

Rel cutoff

Energy

Charge

600

60

-1125.17821812053535

-0.0000000141

700

60

-1125.17827283731867

-0.0000000147

800

60

-1125.17815235733997

-0.0000000121

900

60

-1125.17818711771633

-0.0000000128

1000

60

-1125.17816274805796

-0.0000000131

1100

60

-1125.17813293059771

-0.0000000132

1200

60

-1125.17820271100982

-0.0000000140

1300

60

-1125.17820271126402

-0.0000000141

1400

60

-1125.17817412922477

-0.0000000128

1500

60

-1125.17817458499053

-0.0000000139

I find that the convergence is only till 10**-3 Ha.


On Fri, 17 Mar 2023 at 10:18, Fabian <belleflamme.fabian at gmail.com> wrote:

> Dear Rajorshi,
>
> The original SCAN functional is known to be very sensitive to the
> integration grid used during calculation.
> An easy fix would be to switch to r2SCAN (acs.jpclett.0c02405) instead:
>
>       &XC
>         &XC_FUNCTIONAL
>           &MGGA_X_R2SCAN
>           &END
>           &MGGA_C_R2SCAN
>           &END
>         &END
>       &END XC
>
> Typically, the cutoff should be converged at 1200Ry with SCAN.
>
> Kind regards,
> Fabian
> Rajorshi Chattopadhyay schrieb am Freitag, 17. März 2023 um 00:11:52 UTC+1:
>
>> Dear all,
>>
>> I am trying to do cutoff convergence with the SCAN functional in a
>> aqueous H2O-H2SO4 system. I need an energy convergence of 10**-6 Ha or
>> lower. However, I find that even at a cutoff of 4000Ry (REL_CUTOFF:60),
>> energy convergence is only 10**-4 Ha. The input script is as follows:
>>
>> &GLOBAL
>>
>>     PROJECT Sulphate_amb_dens
>>
>>     RUN_TYPE ENERGY_FORCE
>>
>>     PRINT_LEVEL MEDIUM
>>
>> &END GLOBAL
>>
>> &FORCE_EVAL
>>
>> &DFT
>>
>>       MULTIPLICITY 1
>>
>>       BASIS_SET_FILE_NAME ./BASIS_MOLOPT
>>
>>       POTENTIAL_FILE_NAME ./SCAN_POTENTIALS
>>
>>   &MGRID
>>
>>       CUTOFF 3800
>>
>>       REL_CUTOFF 60
>>
>>       NGRIDS 4
>>
>>   &END MGRID
>>
>>   &SCF
>>
>>      SCF_GUESS ATOMIC
>>
>>      MAX_SCF 3000
>>
>>      EPS_SCF 1.00000000E-007
>>
>>      &OT
>>
>>         MINIMIZER DIIS
>>
>>         PRECONDITIONER FULL_SINGLE_INVERSE
>>
>>      &END OT
>>
>>   &END SCF
>>
>>   &XC
>>
>>      &XC_FUNCTIONAL
>>
>>          &LIBXC
>>
>>           FUNCTIONAL MGGA_X_SCAN
>>
>>          &END LIBXC
>>
>>          &LIBXC
>>
>>            FUNCTIONAL MGGA_C_SCAN
>>
>>            &END LIBXC
>>
>>      &END XC_FUNCTIONAL
>>
>>     &END XC
>>
>>    &END DFT
>>
>>   &SUBSYS
>>
>>     &TOPOLOGY
>>
>>      &CENTER_COORDINATES TRUE
>>
>>      &END CENTER_COORDINATES
>>
>>     &END TOPOLOGY
>>
>>
>>     &CELL
>>
>>        ABC 12.32 12.32 12.32
>>
>>        PERIODIC XYZ
>>
>>     &END CELL
>>
>>     &COORD
>>
>>       @include ../coord_eql
>>
>>    &END COORD
>>
>>    &KIND H
>>
>>       BASIS_SET DZVP-MOLOPT-SR-GTH
>>
>>       POTENTIAL GTH-SCAN-q1
>>
>>    &END
>>
>>    &KIND O
>>
>>       BASIS_SET DZVP-MOLOPT-SR-GTH
>>
>>       POTENTIAL GTH-SCAN-q6
>>
>>    &END
>>
>>   &KIND S
>>
>>       BASIS_SET DZVP-MOLOPT-GTH
>>
>>       POTENTIAL GTH-SCAN-q6
>>
>>    &END
>>
>>
>>   &END SUBSYS
>>
>>  &END FORCE_EVAL
>>
>>
>> I use the pseudopotentials provided by Dr. Joerg Hutter in his github.
>>
>> Am I missing something in the input script ? Is it possible to achieve
>> such tight energy convergences using SCAN the functional?
>>
>> I thank you in advance for your help/suggestions.
>>
>> --
>> With Regards,
>> Rajorshi Chattopadhyay,
>> PhD Researcher in Mineralogy/Crystallography,
>> Institut für Geologie und Mineralogie,
>> Universität zu Köln, Germany
>>
>> --
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>


-- 
With Regards,
Rajorshi Chattopadhyay,
PhD Researcher in Mineralogy/Crystallography,
Institut für Geologie und Mineralogie,
Universität zu Köln, Germany

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