[CP2K-user] [CP2K:12278] Bond breaking during the optimisation

[Patrick Gono]

Dear Nikhil,

I have a couple things to suggest:
1) Your CUTOFF is definitely too small. Please, make sure your model is
converged with respect to your CUTOFF by running a series of single-point
(ENERGY) calculations, as described in:
https://www.cp2k.org/howto:converging_cutoff. In general, the values for
CUTOFF should be in the range of (higher) triple digits, 400 - 800 Ry, or
even more. Whenever possible, make sure you are converged.
2) You are not using any pseudopotential for your Pb and Cs atoms. Look
into the GTH_POTENTIALS file and choose the appropriate one for your choice
of basis sets.
3) Are you sure about your cell parameters? If your plan is to study a
periodic system, you must specify periodic symmetry and choose appropriate
cell parameters. If you plan to simulate an isolated nanoparticle, consider
reducing the size of your cell. 50 angstrom in each direction  might be an
overkill and needlessly slow down your jobs.

Yours sincerely,
Patrick Gono

On Thu, Sep 26, 2019 at 9:01 PM Nikhil Maroli <scin... at gmail.com> wrote:

> The bonds are breaking during the optimization, Initially, i have tried to
> optimize the structure with gaussian but it started to break bonds even at
> correct distances. Anyone can give any suggestion to avoid bond breaking in
> CP2K and to achieve optimized structure.
> Inputs are given below for your information.
> &GLOBAL
>  PROJECT job2
>  RUN_TYPE GEO_OPT
> &END GLOBAL
>
> &FORCE_EVAL
>
>  METHOD QS
>  &DFT
> # Please copy the GTH_BASIS_SETS and POTENTIAL files
> # which may have been in cp2k-x.x.x/data or cp2k-x.x.x/tests/QS directory
> # to the CP2K executable directory if you use these default files.
>    CHARGE 0
>    MULTIPLICITY 2
>   BASIS_SET_FILE_NAME  GTH_BASIS_SETS
>   POTENTIAL_FILE_NAME  POTENTIAL
>   &MGRID
>    NGRIDS 4
>    CUTOFF 30
>   &END MGRID
>   &XC
>    &XC_FUNCTIONAL PBE
>    &END XC_FUNCTIONAL
>   &END XC
>  &END DFT
>  &SUBSYS
>   &COORD
>     Pb         1.94602       -2.12632        1.25157
>     Br         3.01219       -0.06256        2.35356
>     Pb         2.21556        2.03217        1.09683
>     Br        -0.12169        3.23840        1.92449
>     Pb        -2.34714        2.39328        0.99984
>     Br        -3.57990        0.20869        1.95980
>     Pb        -2.65498       -2.14276        1.00547
>     Br        -0.34094       -3.29325        1.98965
>     Pb         2.06448       -1.33415       -1.21263
>     Pb         2.13521        1.12177       -1.15878
>     Br         0.06365        1.19694       -0.08612
>     Pb        -1.79865        1.47428       -1.68114
>     Br        -0.57583       -0.01056       -3.59712
>     Pb        -1.98293       -1.29020       -1.66395
>     Br         0.01062       -1.18331       -0.10788
>     Br        -3.82309       -3.16020       -1.27765
>     Br         3.19291       -3.45179       -0.50642
>     Br        -3.41601        3.49721       -1.28741
>     Cs        -0.28609        0.02294        3.08499
>   &END COORD
>
>    &KIND Br
>     BASIS_SET DZVP-GTH
>     POTENTIAL GTH-PBE-q7
>    &END KIND
>
>    &KIND Cs
>     BASIS_SET DZVP-GTH
>     POTENTIAL # type pseudopotential functional name !
>    &END KIND
>
>    &KIND Pb
>     BASIS_SET DZVP-GTH
>     POTENTIAL # type pseudopotential functional name !
>    &END KIND
>
>   &CELL
>    ABC 50 50 50 # Provisional Cell Param. Please "Add Unit Cell" !
>   &END CELL
>  &END SUBSYS
> &END FORCE_EVAL
>
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