[CP2K-user] [CP2K:18104] Re: Not getting correct optimised geometry for Au(111) surface with ligands (BDT or DMBT)

[Marcella Iannuzzi]

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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