[CP2K:7757] BSSE Calculation while using two copper types

[S. Ling]

Correction: You should calculate the BSSE-corrected binding energy with 
both "monomers" in the dimer geometry (this is what &BSSE does in CP2K), 
not from independently optimised "monomer" geometry (your first 
calculation), especially if the host-guest interaction is strong. See this 
document for more 
discussion, http://vergil.chemistry.gatech.edu/notes/cp.pdf

As I pointed out, the electronic configuration of Cu2+ ions will affect the 
host-guest interaction in your case, so you will need to set up the 
electronic configurations correctly.

SL


On Monday, May 16, 2016 at 5:06:34 PM UTC+1, S Ling wrote:
>
> Hi Chris,
>
> This is not a CP2K-specific question. It is about how you would like to 
> define the BSSE-corrected interaction energy between two "monomers". In the 
> original counterpoise scheme by Boys and Bernardi, the geometries of the 
> two "monomers" were fully optimised with the "dimer" basis. In CP2K, you 
> will have to set up some GHOST atoms manually in order to relax the monomer 
> geometries with "dimer" basis. One approximation you can make is that you 
> calculate the interaction energy at fixed monomer geometries in the 
> "dimer", i.e. you neglect the geometry relaxations of both "monomers" due 
> to additional basis sets on GHOST atoms, and this is exactly what CP2K is 
> doing. In some other quantum chemistry codes (e.g. Gaussian), the geometry 
> relaxations of monomers may be automatically taken into account if you 
> switch on the counterpoise correction scheme.
>
> BTW: You didn't break the symmetry in the electronic configuration of Cu 
> ions, and currently you have a closed-shell singlet solution. Are you sure 
> that's the electronic ground state?
>
> SL
>
>
>
> On 16 May 2016 at 13:15, Chris Campbell <chri... at gmail.com <javascript:>> 
> wrote:
>
>> Afternoon SL,
>>
>> Apologies for the hassle but wondered if I could quickly ask a follow up 
>> question.
>>
>> Initially for my system using a PBE functional I optimised my Adsorbent 
>> and Adsorbate independently and then together, when i found the difference 
>> I got an interaction energy of ~25kJ/mol.
>>
>> Following this BSSE fragment Calculation (using the fully optimised 
>> combination of Adsorbent and Adsorbate together), I get a value in the 
>> output of BSSE-free interaction energy: ~-20kJ/mol, which seems very 
>> reasonable (to me).
>>
>> This energy, however , calculated for the Adsorbate and adsorbent is not 
>> from the independent optimisation positions so can I use this energy? or do 
>> I have to work backwards to calculate the BSSE correction and then apply it 
>> to the original -25kJ/mol?
>>
>> Apologies if this is not worded very clearly.
>>
>> Kindest Regards,
>> Chris
>>
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