[CP2K-user] [CP2K:18110] Re: Not getting correct optimised geometry for Au(111) surface with ligands (BDT or DMBT)

Vikash Khokhar vikashkhokhar141 at gmail.com
Tue Nov 29 12:22:42 UTC 2022


Thank you, Marcella
I'll look into this. 

Regards 
Vikash

On Tuesday, November 29, 2022 at 5:45:58 PM UTC+5:30 Marcella Iannuzzi 
wrote:

> Dear Vikash
>
> In the posted input, the k-points are not used. 
> If you already used them, try with a denser mesh and with the *MONKHORST-PACK 
> scheme.*
> I suggest that you test on one configuration (possibly already a bit 
> distorted) the effects on energies and forces by changing k-point mesh and 
> cutoff.
> If energies and forces are not accurate, the geometry will be wrong. 
> EPS_SCF 1.0E-07 should be good enough.
> OUTER_SCF is used only to reinitialise the preconditioner for the OT 
> approach, hence it is useless with the standard diagonalization method.
>  3 layers for a Au slab are insufficient and are keen to lead to weird 
>  distortions in the lattice. 
>
> Regards
> Marcella
>  
>
>
> On Tuesday, November 29, 2022 at 5:58:54 AM UTC+1 vikashkh... at gmail.com 
> wrote:
>
>> Thank you, Marcella, 
>> I would like to know the exact PW cutoff I can use.
>> And yes, I  have used mesh k-points 2 3 1, are these correct, or do I 
>> need to take a bigger grid? If yes, what should it be?
>> I thought the default tolerance would be okay. If not, then how much 
>> tolerance would be enough?
>>
>> Regards 
>> Vikash
>> On Monday, November 28, 2022 at 8:17:19 PM UTC+5:30 Marcella Iannuzzi 
>> wrote:
>>
>>> dear Vikash
>>>
>>> The system is probably too small.
>>> To stabilise the Au slab one should use more layers, we use 6.
>>> With such small lateral dimension you should use a mesh of k-points. 
>>> Moreover, the tolerance for the convergence of the wavefunction is not 
>>> very tight  and the PW cutoff seems quite low. 
>>>
>>> Regards
>>> Marcella
>>>
>>> On Monday, November 28, 2022 at 1:58:13 PM UTC+1 vikashkh... at gmail.com 
>>> wrote:
>>>
>>>> I'm trying to optimize a small unit cell of  Au(111) surface with 
>>>> ligands (BDT or DMBT) but I'm not getting the correct optimized geometry.
>>>> I'm using Cp2k 8.1 version.
>>>> I'm attaching the Input file here, please have a look and suggest to me 
>>>> what's wrong with my calculation. 
>>>>
>>>> &GLOBAL
>>>>   PROJECT Au_64_2BDT
>>>>   RUN_TYPE GEO_OPT
>>>>   PRINT_LEVEL MEDIUM
>>>> &END GLOBAL
>>>>
>>>> &MOTION
>>>>   &GEO_OPT
>>>>     TYPE MINIMIZATION
>>>>     OPTIMIZER BFGS
>>>>     MAX_DR    3.00E-03
>>>>     MAX_FORCE 4.50E-04
>>>>     RMS_DR    1.50E-03
>>>>     RMS_FORCE 3.00E-04
>>>>     MAX_ITER 3000
>>>>   &END GEO_OPT
>>>>
>>>>   &CONSTRAINT
>>>>     &FIXED_ATOMS
>>>>       COMPONENTS_TO_FIX XYZ
>>>>       LIST 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 
>>>> 24
>>>>     &END FIXED_ATOMS
>>>>   &END CONSTRAINT
>>>>
>>>> &END MOTION
>>>>
>>>> &FORCE_EVAL
>>>>   METHOD QS
>>>>
>>>>   &DFT
>>>>     BASIS_SET_FILE_NAME BASIS_MOLOPT
>>>>     POTENTIAL_FILE_NAME GTH_POTENTIALS
>>>>
>>>>     &QS
>>>>       METHOD GPW
>>>>       EXTRAPOLATION USE_GUESS
>>>>       EPS_DEFAULT 1.0E-10
>>>>     &END QS
>>>>
>>>>     &MGRID
>>>>       CUTOFF 350
>>>>       NGRIDS 4
>>>>       REL_CUTOFF 60
>>>>     &END MGRID
>>>>
>>>>     &SCF
>>>>       SCF_GUESS ATOMIC
>>>>       EPS_SCF 1.0E-05
>>>>       MAX_SCF 200
>>>>       ADDED_MOS 10
>>>>
>>>>       &OUTER_SCF
>>>>        EPS_SCF 1.0E-04
>>>>        MAX_SCF 200
>>>>       &END OUTER_SCF
>>>>
>>>>       &DIAGONALIZATION T
>>>>         ALGORITHM STANDARD
>>>>       &END DIAGONALIZATION
>>>>
>>>>       &SMEAR ON
>>>>         METHOD FERMI_DIRAC
>>>>         ELECTRONIC_TEMPERATURE [K] 300
>>>>       &END SMEAR
>>>>
>>>>       &MIXING T
>>>>         METHOD BROYDEN_MIXING
>>>>         ALPHA 0.4
>>>>         NBROYDEN 8
>>>>       &END MIXING
>>>>     &END SCF
>>>>
>>>>     &XC
>>>>       &XC_FUNCTIONAL PBE
>>>>       &END XC_FUNCTIONAL
>>>>
>>>>       &vdW_POTENTIAL
>>>>         DISPERSION_FUNCTIONAL PAIR_POTENTIAL
>>>>         &PAIR_POTENTIAL
>>>>             PARAMETER_FILE_NAME dftd3.dat
>>>>             TYPE DFTD3
>>>>             REFERENCE_FUNCTIONAL PBE
>>>>             R_CUTOFF 25.0
>>>>         &END PAIR_POTENTIAL
>>>>      &END vdW_POTENTIAL
>>>>     &END XC
>>>>
>>>>     &KPOINTS
>>>>       SCHEME GAMMA 1 1 1
>>>>       FULL_GRID .TRUE.
>>>>       PARALLEL_GROUP_SIZE  0
>>>>     &END KPOINTS
>>>>
>>>>   &END DFT
>>>>
>>>>   &SUBSYS
>>>>     &CELL
>>>>       PERIODIC XYZ
>>>>       A    17.3099747000000015    0.0000000000000000   
>>>>  0.0000000000000000
>>>>       B     0.0000000000000000    9.9939184000000001   
>>>>  0.0000000000000000
>>>>       C     0.0000000000000000    0.0000000000000000   
>>>> 30.0000000000000000
>>>>     &END CELL
>>>>
>>>>     &COORD
>>>>       @INCLUDE Au_64_2BDT.xyz
>>>>     &END COORD
>>>>
>>>>     &KIND Au
>>>>       BASIS_SET DZVP-MOLOPT-SR-GTH
>>>>       POTENTIAL GTH-PBE
>>>>     &END KIND
>>>>     &KIND H
>>>>       BASIS_SET DZVP-MOLOPT-GTH
>>>>       POTENTIAL GTH-PBE
>>>>     &END KIND
>>>>     &KIND C
>>>>       BASIS_SET DZVP-MOLOPT-GTH
>>>>       POTENTIAL GTH-PBE
>>>>     &END KIND
>>>>     &KIND S
>>>>       BASIS_SET DZVP-MOLOPT-GTH
>>>>       POTENTIAL GTH-PBE
>>>>     &END KIND
>>>>   &END SUBSYS
>>>> &END FORCE_EVAL
>>>>
>>>> I'm also attaching the input and output geometry pics. In the input 3rd 
>>>> layer of the gold surface is fixed and the above 2 layers optimize above 
>>>> each other(which breaks 111 symmetry) which is not expected.
>>>> I hope you understand my problem and I expect a solution, earliest 
>>>> possible. 
>>>>
>>>> Regards 
>>>> Vikash Khokhar
>>>> Indian Institute of Technology, Madras [image: Screenshot from 
>>>> 2022-11-28 18-24-10.png][image: Screenshot from 2022-11-28 
>>>> 18-25-47.png]
>>>>
>>>

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