[CP2K-user] [CP2K:21243] Re: Calculating binding energy

[Quentin Pessemesse]

Hello again,

Maybe I'm visualizing wrong, but it looks to me like the "adsorbed" 
ammonia molecule did not optimize to the structure you wanted. It looks 
like you have a molecule split on either side of the graphene sheet. If 
this is what you meant to do, it's fine, otherwise you need to rebuild 
it. It looks like you did not re-optimize either the ammonia molecule or 
the graphene sheet, which you must do if you want to have meaningful 
energetics. Right now, you are seeing that starting from an extremely 
distorted NH3 and a distorted graphene, it is much much favorable to 
adsorb on graphene, which makes sense but does not give you the 
information you want.

Take care :)

Quentin

On 04/03/2025 06:42, Oksana Grinevich wrote:
>> nh3_last - optimization file
>> nh3last_1 - energy for optimized geometry of bonded system
>> nh3last_3 - energy for optimized geometry of lone graphene
>> nh3G24_2 - energy of lone ammonia on a distance (imitation of 
>> infinity distance)
>
> воскресенье, 2 марта 2025 г. в 22:41:59 UTC+3, Quentin Pessemesse:
>
>     Hello,
>     Could you please send the .inp files so that I can have a look ?
>     It looks like maybe something went wrong with the geometry
>     optimization of either your lone components or your adduct.
>     Best,
>     Quentin
>
>     Le mercredi 26 février 2025 à 13:22:13 UTC+1, Oksana Grinevich a
>     écrit :
>
>         I am running calculations to obtain binding energy of a
>         molecule on the graphene sheet. After obtaining the energy
>         value of this system (bonded), I calculate the energy values
>         for lone molecule and lone graphene atoms (I tried with the
>         same coordinates and varying them). Thus, I can roughly find
>         the excess (adsorption) energy as follows:
>
>         E (excess)=E(bonded)-E(lone molecule)-E(lone graphene)
>
>         After this step I want to convert this energy to kJ/mol
>         (*2625.5). It worked pretty well for benzene on graphene
>         (obtained 40 kJ/mol) and other aromatic structures but for
>         ammonia and triethylamine I can obtain something like 700
>         kJ/mol or even more which seems not physically corrected values.
>
>         I would like to know where I did wrong and what can I do to
>         improve results.
>
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