[CP2K-user] [CP2K:16423] Re: Cell Optimization of Platinum (Pt) with fcc (111) surface

[Fabian Ducry]

Dear Geng,

You should decrease eps_scf to 1e-7 or 1e-8. The default 1e-6 is good 
for the initial stage of the optimization, when the forces/pressure are 
still large. Later on this should be adjusted, especially if you request 
such tight convergence criteria in &CELL_opt. Decreasing this value 
reduces the noise in the forces and improves the convergence of the cell 
optimization.

Cheers,

Fabian


On 03.01.2022 21:40, GENG YUAN wrote:
> Here are the screenshots.
> beforecellopt_view1.pngaftercellopt_view1.png
> Top view before cell optimization                                     
>           Top view after cell optimization
>
> beforecellopt_view2.pngaftercellopt_view2.png
> Another view before cell optimization                                 
>            Another view after cell optimization
>
> Sincerely,
> Geng
>
> 在2022年1月3日星期一 UTC-5 15:34:56<GENG YUAN> 写道：
>
>     Dear CP2K Users,
>
>     Hope you are going great and happy new year.
>
>     I am running the cell optimization for a single bulk Pt (134
>     atoms) with fcc 111 surface. By checking my output file, I notice
>     that the cell optimization takes 446 steps to converge (which is
>     almost close to the maximum number of optimization steps:500).
>     Besides, a certain degree of structure deformation is observed
>     during optimization (please see the attached files and screenshots).
>
>     I am wondering if there are any other ways to let the cell
>     optimization converge faster (in other words, converge in fewer
>     steps) and whether the above-mentioned deformation looks reasonable?
>     Below is the input: (attached are input file, output file,
>     original coordinate, trajectory, and the screenshots of the
>     trajectory)
>     ------------------------------------------------------------
>     &GLOBAL
>       PROJECT Pt_cellopt
>       RUN_TYPE CELL_OPT
>       PRINT_LEVEL LOW
>     &END GLOBAL
>     &FORCE_EVAL
>       METHOD QS
>       STRESS_TENSOR ANALYTICAL
>       &SUBSYS
>         &CELL
>           ABC 13.7 13.7 13.7
>           SYMMETRY CUBIC
>          &CELL_REF
>           ABC 13.7*1.5 13.7*1.5 13.7*1.5
>          &END
>         &END CELL
>         &TOPOLOGY
>          COORD_FILE_NAME ./Pt134.xyz
>          COORDINATE xyz
>         &END
>         &KIND Pt
>           BASIS_SET DZVP-MOLOPT-SR-GTH
>           POTENTIAL GTH-PBE-q18
>         &END KIND
>       &END SUBSYS
>       &DFT
>         BASIS_SET_FILE_NAME ./BASIS_MOLOPT
>         POTENTIAL_FILE_NAME ./GTH_POTENTIALS
>         &QS
>           EPS_DEFAULT 1.0E-12
>         &END QS
>         &MGRID
>           CUTOFF 400
>           NGRIDS 5
>           REL_CUTOFF 40
>         &END MGRID
>         &SCF
>           SCF_GUESS ATOMIC
>           EPS_SCF 1.0E-06
>           MAX_SCF 200
>           ADDED_MOS 100
>           &OUTER_SCF
>             MAX_SCF 50
>             EPS_SCF 1.0E-6
>           &END
>           &DIAGONALIZATION T
>             ALGORITHM STANDARD
>           &END DIAGONALIZATION
>           &MIXING T
>             METHOD BROYDEN_MIXING
>             ALPHA 0.1
>             NBROYDEN 8
>           &END MIXING
>           &SMEAR ON
>             METHOD FERMI_DIRAC
>             ELECTRONIC_TEMPERATURE [K] 500
>           &END SMEAR
>           &PRINT
>             &RESTART ON
>             &END RESTART
>           &END PRINT
>         &END SCF
>         &XC
>           &XC_FUNCTIONAL
>              &LIBXC
>                FUNCTIONAL XC_GGA_X_PBE_R
>              &END
>              &LIBXC
>                FUNCTIONAL XC_GGA_C_PBE
>              &END
>           &END XC_FUNCTIONAL
>           &VDW_POTENTIAL
>              POTENTIAL_TYPE PAIR_POTENTIAL
>              &PAIR_POTENTIAL
>                 LONG_RANGE_CORRECTION
>                 PARAMETER_FILE_NAME dftd3.dat
>                 TYPE DFTD3
>                 REFERENCE_FUNCTIONAL revPBE
>              &END PAIR_POTENTIAL
>            &END VDW_POTENTIAL
>            &XC_GRID
>             XC_DERIV NN50_SMOOTH
>            &END XC_GRID
>         &END XC
>       &END DFT
>     &END FORCE_EVAL
>     &MOTION
>       &CELL_OPT
>         EXTERNAL_PRESSURE 0
>         TYPE DIRECT_CELL_OPT
>         KEEP_SYMMETRY TRUE
>         MAX_DR    1.0E-05
>         MAX_FORCE 1.0E-05
>         RMS_DR    1.0E-05
>         RMS_FORCE 1.0E-05
>         MAX_ITER 500
>         OPTIMIZER BFGS
>       &END CELL_OPT
>     &END MOTION
>
>     Many thanks in advance,
>     Sincerely,
>     Geng
>
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