Dear 

You can calculate the BSSE error of the energy after optimization. You edit the optimize structure and on the right corner clique on the icon and you will se the BSSE approximation. You run only energy and you will find the correction.

Good luck 

Thank you, I already calculated the BSSE value, but i do not know how to use it to correct the error in the ∆G values that i have computed.

Mrs/Miss/Mr Sh,

By frequency analysis.

Dear Ema,

within BSSE analysis you can obtain "corrected energy" printed out at the end of calculation. Indeed, this values is the corrected "total electronic energy (Eele) " of your system:

Eele(corrected)= Eele(non-corrected)+BSSE energy

The first and second terms in the right hand-side of the given equation is, respectively, total electronic energy you obtain via optimization and the BSSE energy printed out at the end of BSSE analysis. Very simply, if you add Eele(corrected) to the "thermal correction to Gibbs free energy" taken from frequency calculation, corrected "sum of electronic and thermal free energy (GT/corrected)" will be obtained.

Best,

Saeed   

Thank you very much, i'll try it your suggestion right away.The Gibbs free energy value that i'll obtain will be corrected for both BSSE and zero point, but won't it equate the direct addition of the BSSE correction value to the "Sum of electronic and thermal Free Energies" ?

OK. Let me to know if your problem still remains unresolved.

Good Luck!

I tried the formula. The direct addition of BSSE correction value to "Sum of electronic and Thermal free energies" and the Eele(non-corrected)+BSSE energy + thermal correction to Gibbs free energy yielded the same results for both systems AB and AB2.

It confirms my previous results, and i can proceed onwards with my calculations . Everyone, thank you very much for your advices. If there other ways to correct the Gibbs free binding/adsorption energy of a hydrogen bonded system, please let me know.

Ema, Sh

Mrs/Miss/Mr Sh,

In addition:

Chem. Sci., 2012, 3, 3526–3533

Thank you for the link

Ema Sh

Please you can find the solution in the Fiona Sim paper: Fiona Sim, Alain St Amant Imre Papal.  J. Am. Chem. Soc..  1992, 114,  4391-4400

Good Luck

Thank you for your help.

Ema Sh

Mr. Sh,

Yin addition:

You should add to the route section 'counter=2 freq'.

After each of the coordinates of the atoms in the 'molecule specification section' you should add 1 or 2.

You could pay attention to an example, taken from the Gaussian' manual how to incorporate '1' and '2':

# HF/LANL2DZ Counterpoise=2 NoSymm Opt

0 1

H(Fragment=1) -0.046866 0. 0.586860

Br(Fragment=1) -0.331864 0. -0.801000

F(Fragment=2) 0.396755 0. 2.739275

H(Fragment=2) 0.584835 0. 3.641534

Counterpoise Output:

Counterpoise: corrected energy = -2660.083831739527

Counterpoise: BSSE energy = 0.003902746890

Hi Ema,

The input file should be entered as fragments: in this case, there is a few software which can do it for you, such as gaussView or crystallography pros. 

Also, you need to add this command to the route line: 

Counterpoise=2 NoSymm Opt

This issue arises in the dissociation Eng.  with monomers and dimers. 

Best!