[CP2K-user] [CP2K:13120] SCAN XC density functional: Do we have to use specific PSEUDOPOTENTIALS for SCAN? Are they available?
Thomas Kühne
tku... at gmail.com
Mon Apr 13 19:14:52 UTC 2020
Dear Slava,
I understand. What I wanted to say that these things are only very weakly related.
Instead of tempting around with the density cutoff values, try to improve the SCF
section, or directly change to a diagonalization based eigenvalue solver.
Using OT, you may try to reduce MAX_SCF to 50 for instance, reduce stepsize
and energy_gap …
Cheers,
Thomas
> Am 13.04.2020 um 21:01 schrieb Vyacheslav Bryantsev <vyachesla... at gmail.com>:
>
> Dear Thomas.
>
> I am familiar with this tutorial.
> The purpose for having so high CUTOFF and REL_CUTOFF is not to get the converged results, but simply be able to converge SCF for consecutive MD steps.
> For example, using CUTOFF 1500 and REL_CUTOFF 200 would give converged SCF cycles taking 1000s of steps for consecutive MD steps. Less than 10 SCF would be needed by using CUTOFF 2300, as was empirically found.
> I will be happy to provide complete input files, if needed.
>
> Thank you,
> Slava
>
>
> On Monday, April 13, 2020 at 2:11:55 PM UTC-4, tkuehne wrote:
> Dear Vyacheslav,
>
> such a large density cutoff strikes me as odd. SCF convergence behavior isn’t
> a good indicator to converge CUTOFF and REL_CUTOFF. Please have a look
> at: https://www.cp2k.org/howto:converging_cutoff <https://www.cp2k.org/howto:converging_cutoff>
> IMHO, Total charge density on r- and g-space grids are
> much stronger indicators …
>
> Cheers,
> Thomas
>
>> Am 13.04.2020 um 19:55 schrieb Vyacheslav Bryantsev <vyac... at gmail.com <>>:
>>
>> Dear Juerg and All,
>>
>> Here I provide an update for a large band gap system, consisting of Mg2+ and Cl- ions (molten salt).
>> Very high CUTOFF 2300 and REL_CUTOFF 100 were necessary to get converged SCF results with SCAN-D3 XC, suitable for MD.
>> Using lower cutoffs, such as CUTOFF 2000 and REL_CUTOFF 100 were not sufficient, because it required more > 100 SCF steps for some fraction of MD steps, which is not acceptable. Because of that, the average time for AIMD was higher than for the case with CUTOFF 2300.
>>
>> The portion of used input file is shown below. The average time for each SCF step is 5-6 times slower compared to PBE-D3.
>> Is this the expected behavior? Are there any ways I can explore to speed up SCAN-D3 calculations, used in the context of AIMD.
>>
>> Thank you,
>> Slava
>>
>> &MGRID
>>
>> CUTOFF 2300
>>
>> REL_CUTOFF 100
>>
>> ! NGRIDS 4
>>
>> &END MGRID
>>
>> &SCF
>>
>> MAX_SCF 150
>>
>> EPS_SCF 3.5E-6
>>
>> SCF_GUESS RESTART
>>
>> &OUTER_SCF
>>
>> EPS_SCF 3.5E-6
>>
>> MAX_SCF 40
>>
>> &END
>>
>> &OT T
>>
>> MINIMIZER CG
>>
>> PRECONDITIONER FULL_ALL
>>
>> &END OT
>>
>>
>> &END SCF
>>
>>
>> &XC
>>
>> &XC_FUNCTIONAL
>>
>> &LIBXC
>>
>> FUNCTIONAL MGGA_X_SCAN
>>
>> &END LIBXC
>>
>> &LIBXC
>>
>> FUNCTIONAL MGGA_C_SCAN
>>
>> &END LIBXC
>>
>> &END XC_FUNCTIONAL
>>
>> &vdW_POTENTIAL
>>
>> DISPERSION_FUNCTIONAL PAIR_POTENTIAL
>>
>> &PAIR_POTENTIAL
>>
>> R_CUTOFF 40.0
>>
>> TYPE DFTD3
>>
>> D3_SCALING 1.0 1.324 0.0
>>
>> PARAMETER_FILE_NAME dftd3.dat
>>
>> ! REFERENCE_FUNCTIONAL SCAN
>>
>> &END PAIR_POTENTIAL
>>
>> &END vdW_POTENTIAL
>>
>> &END XC
>>
>>
>> &END DFT
>>
>>
>>
>> &SUBSYS
>>
>> &CELL
>>
>> ABC 24.450 24.450 24.450
>>
>> PERIODIC XYZ
>>
>> &END CELL
>>
>> &TOPOLOGY
>>
>> COORD_FILE_FORMAT XYZ
>>
>> COORD_FILE_NAME last_frame_wrapped.xyz <http://last_frame_wrapped.xyz/>
>> &END TOPOLOGY
>>
>> &KIND Mg
>>
>> BASIS_SET DZVP-MOLOPT-SR-GTH
>>
>> POTENTIAL GTH-SCAN-q10
>>
>> &END KIND
>>
>> &KIND Cl
>>
>> BASIS_SET DZVP-MOLOPT-SR-GTH
>>
>> POTENTIAL GTH-SCAN-q7
>>
>> &END KIND
>>
>>
>> &END SUBSYS
>>
>>
>>
>>
>> On Monday, April 13, 2020 at 10:09:19 AM UTC-4, Vyacheslav Bryantsev wrote:
>> Dear Juerg and All,
>>
>> Thank you for recommendations.
>> With regards to very high cutoffs, what should I try?
>>
>> I startred with CUTOFF 600 and REL_CUTOFF 100, and this does not seem to work.
>> Which setting would you recommends for SCAN XC?
>>
>> Thank you,
>> Slava
>>
>>
>> &MGRID
>>
>> CUTOFF 600
>>
>> REL_CUTOFF 100
>>
>> &END MGRID
>>
>> &SCF
>>
>> MAX_SCF 150
>>
>> EPS_SCF 1.0E-6
>>
>> SCF_GUESS RESTART
>>
>> &OUTER_SCF
>>
>> EPS_SCF 1.0E-6
>>
>> MAX_SCF 40
>>
>> &END
>>
>> &OT T
>>
>> MINIMIZER CG
>>
>> PRECONDITIONER FULL_ALL
>>
>> &END OT
>>
>>
>>
>>
>> On Friday, April 10, 2020 at 6:31:42 AM UTC-4, jgh wrote:
>> Hi
>>
>> 1) Many people have used PBE pp previously.
>> SCAN optimized pp can be found at
>> https://github.com/juerghutter/GTH/blob/master/SCAN/POTENTIAL <https://github.com/juerghutter/GTH/blob/master/SCAN/POTENTIAL>
>> 2) Newly published SCAN parameters for D3 are available in the current
>> version of CP2K from Github. For older version you need to
>> add a line in the input with the parameters.
>> 3) Use very high cutoffs, depending on your system. If the cutoff is not
>> high enough SCF will not converge smoothly to a low value (10^-7 in OT).
>> I don't have experience if the smoothing methods work to reduce the cutoff.
>>
>> regards
>>
>> Juerg Hutter
>> --------------------------------------------------------------
>> Juerg Hutter Phone : ++41 44 635 4491
>> Institut für Chemie C FAX : ++41 44 635 6838
>> Universität Zürich E-mail: h... at chem.uzh.ch <>
>> Winterthurerstrasse 190
>> CH-8057 Zürich, Switzerland
>> ---------------------------------------------------------------
>>
>> -----c... at googlegroups.com <> wrote: -----
>> To: "cp2k" <c... at googlegroups.com <>>
>> From: "Vyacheslav Bryantsev"
>> Sent by: c... at googlegroups.com <>
>> Date: 04/09/2020 04:50PM
>> Subject: [CP2K:13100] SCAN XC density functional: Do we have to use specific PSEUDOPOTENTIALS for SCAN? Are they available?
>>
>> Dear CP2K Community,
>>
>> Is there a set or recommended setting for using SCAN in cp2k?
>>
>> More specifically,
>> 1. Can we use PBE pseudopotentials for SCAN or this is a bad idea? If not, where one can find specific pseudopotentials reparametrized for SCAN?
>> 2. Does the D3 correction work automatically now with SCAN. If not, how to specify it?
>> 3. Recommendations for grid when using SCAN
>>
>> Thank you,
>> Slava
>>
>>
>>
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>>
>>
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==============================
Thomas D. Kühne
Dynamics of Condensed Matter
Chair of Theoretical Chemistry
University of Paderborn
Warburger Str. 100
D-33098 Paderborn
Germany
tdku... at mail.upb.de
+49/(0)5251/60-5726
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