[CP2K-user] [CP2K:21646] Re: Upward Relaxation of Au Surface Atoms in C₆₀-on-Au(111) Geometry Optimization (CP2K v8.0)

[hamid zabihi]

Dear all,

Thank you very much for your helpful insights and suggestions.

Based on your comments, I now realize that the slab I initially constructed
was incorrectly terminated—more representative of a (100) surface rather
than Au(111). Additionally, the excessive lateral cell dimensions likely
contributed to nonphysical behavior, effectively causing the slab to behave
like a cluster during optimization.

I have now reconstructed the slab with correct Au(111) termination,
appropriate lattice constants, and reduced lateral vacuum. I also applied
constraints to fix the bottom two layers (32 atoms) to stabilize the slab.
However, despite these corrections, I still observe significant
restructuring during the geometry optimization of the Au slab *alone*, even
without the C₆₀ molecule.

To facilitate further advice, I will attach the updated input file and
trajectory from this latest attempt.

Thank you again for your support.

Best regards,
Hamid Zabihi

On Wed, Jul 9, 2025 at 1:27 PM Daniele Passerone <dpasserone at gmail.com>
wrote:

> Hi, there are at least a couple of problems in your input files.
>
> The first one is the one mentioned by marcella: The termination is a 100,
> that is going to reconstruct to increase the lateral density (to a
> triangular close packed layer).
> The other one is that your cell has a lateral dimension
>
>     &CELL
>       ABC 22.9836444855 40.0 22.9836444855
>       PERIODIC XZ
>     &END CELL
>
> And since the default (see manual
> https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/SUBSYS/CELL.html
>
> ) is Angstrom, your system has a lot of empty space laterally, and this is
> seen in the optimization trajectory where the not-fixed atoms are behaving
> like a cluster and not as a slab.
>
> HTH
>
> Daniele
>
>
> On Wednesday, July 9, 2025 at 11:50:20 AM UTC+2 Marcella Iannuzzi wrote:
>
>> Hi Hamid,
>>
>> Are you sure that the Au coordinates correspond to a Au(111) slab?
>> I just had a quick look, but the staking looks weird.
>>
>> Regards
>> Marcella
>>
>> On Wednesday, July 9, 2025 at 6:47:51 AM UTC+2 hamidzabihi... at gmail.com
>> wrote:
>>
>>> Dear CP2K community,
>>>
>>> I am performing a geometry optimization of a *C₆₀ molecule adsorbed on
>>> an Au(111) slab*, using *PBE+D3* and *DZVP-MOLOPT-SR-GTH* basis sets.
>>>
>>> The initial configuration had C₆₀ placed ~3 Å above the gold surface.
>>> However, after optimization, I noticed that *several top-layer Au atoms
>>> were pulled significantly upward*—toward the C₆₀. This distortion seems
>>> nonphysical and may indicate issues with my setup or parameters.
>>>
>>> I would be grateful for any advice on:
>>>
>>>    -
>>>
>>>    Best practices for modeling *molecule-surface interactions* in CP2K
>>>    -
>>>
>>>    Ensuring *slab stability* and correct *adsorption behavior*
>>>    -
>>>
>>>    Whether this is a known issue with this CP2K version or functional
>>>
>>> *System details:*
>>>
>>>    -
>>>
>>>    CP2K version: 8.0 (development)
>>>    -
>>>
>>>    Functional: PBE with D3 dispersion correction
>>>    -
>>>
>>>    Basis sets: DZVP-MOLOPT-SR-GTH
>>>    -
>>>
>>>    Slab: 4-layer Au(111), ~15 Å vacuum in y-direction, bottom layers
>>>    unconstrained
>>>
>>> I’ve attached the following files:
>>>
>>>    -
>>>
>>>    cp2k_c60_au_geoopt.inp: Input file
>>>    -
>>>
>>>    out-C60_Au_GEO_OPT.log: Optimization output
>>>    -
>>>
>>>    C60_Au_opt-trajectory.xyz-pos-1: Final trajectory
>>>
>>> Thank you in advance for your help!
>>>
>>> Best regards,
>>> *Hamid Zabihi*
>>>
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