[CP2K-user] [CP2K:12336] cutoff-convergence

Patrick Gono patri... at gmail.com
Thu Oct 10 18:44:48 UTC 2019

```Dear Malik,

You might consider further increasing the CUTOFF. Values up to higher
triple digits might be necessary to completely converge your energies
depending on the system you are simulating.

Yours sincerely,
Patrick Gono

On Thu, 10 Oct 2019, 13:13 Akshay Malik, <akshayma... at gmail.com> wrote:

> Dear all,
> I am trying to do cutoff-convergence for my system but it is only
> converging up to two digits after the decimal point.
> Please suggest some method by which I can get converged energy up to 6
> decimals.
>
> # Grid cutoff vs total energy
> # Date: Thu Oct 10 16:37:32 IST 2019
> # PWD: /home/space/cp2k/cutoff-convergence
> # REL_CUTOFF = 60
> # Cutoff (Ry) | Total Energy (Ha) | NG on grid 1 | NG on grid 2 | NG on
> grid 3 | NG on grid 4
>      50.00  -1337.8915343935  668903   50882     240       0
>     100.00  -1351.0266889654  1216132  286203   11290       0
>     150.00  -1351.6349634609  1071797  364690   75938    1200
>     200.00  -1351.6825629692  975942  418150  115933    3600
>     250.00  -1351.6992612267  875755  439820  192650    5400
>     300.00  -1351.6990099247  791971  424161  286203   11290
>     350.00  -1351.6961310939  735698  431201  323555   23171
>     400.00  -1351.6944391280  687700  428173  341928   55824
>     450.00  -1351.6933108152  644645  427152  364690   77138
>     500.00  -1351.6931016574  603223  441589  368145  100668
>
> I am using this cp2k file section for calculating energy:
> &FORCE_EVAL
>   METHOD Quickstep
>   &DFT
>     BASIS_SET_FILE_NAME  GTH_BASIS_SETS
>     POTENTIAL_FILE_NAME  GTH_POTENTIALS
>     &MGRID
>       NGRIDS 4
>       CUTOFF LT_cutoff
>       REL_CUTOFF LT_rel_cutoff
>     &END MGRID
>     &QS
>       EPS_DEFAULT 1.0E-10
>     &END QS
>     &SCF
>       SCF_GUESS ATOMIC
>       EPS_SCF 1.0E-6
>       MAX_SCF 1
>       CHOLESKY INVERSE
>       &SMEAR ON
>         METHOD FERMI_DIRAC
>         ELECTRONIC_TEMPERATURE [K] 333
>       &END SMEAR
>       &DIAGONALIZATION
>         ALGORITHM STANDARD
>       &END DIAGONALIZATION
>       &MIXING
>         METHOD BROYDEN_MIXING
>         ALPHA 0.4
>         BETA 0.5
>         NBROYDEN 8
>       &END MIXING
>     &END SCF
>      &XC
>       &XC_FUNCTIONAL BLYP
>       &END
>     &END
>   &END DFT
>
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