[CP2K-user] [CP2K:16430] Re: Cell Optimization of Platinum (Pt) with fcc (111) surface

Lucas Lodeiro elunicolomo at gmail.com
Wed Jan 5 21:00:16 UTC 2022


Hi,

I usually set the same EPS_SCF value at the SCF and OUTER_SCF section.
Also, I read somewhere (I do not remember), EPS_SCF cannot be less than the
square root of EPS_DEFAULT. I guess EPS_DEFAULT 1E-16 and EPS_SCF 1E-8
could converge with less cycles, but the time amount per cycle will be
higher.

regards - Lucas

El mié, 5 ene 2022 a las 17:49, GENG YUAN (<yuangeng0821 at gmail.com>)
escribió:

> Dear Fabian,
>
> Many thanks for your advice!
> I decrease eps_scf (under &SCF section) to 1e-8 (the old setting is 1e-6)
> and found that this didn't improve the convergence of the cell
> optimization. It took 433 steps to converge, and the overall simulation
> running time also increased.
>
> Attached are the new input, output, and trajectory for your reference.
>
> Please let me know if any thoughts.
> Sincerely,
> Geng
>
> 在2022年1月3日星期一 UTC-5 16:03:37<fabia... at gmail.com> 写道:
>
>> 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.
>> [image: beforecellopt_view1.png][image: aftercellopt_view1.png]
>> Top view before cell optimization
>>                                   Top view after cell optimization
>>
>> [image: beforecellopt_view2.png][image: aftercellopt_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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