Dear Ranga,

If you would like to calculate a binding energy of compound A with Compound (entity) B by G09, you should do the following:

1-Calculate the global minimum structure of A using opt and frequency

2-Calculate the global minimum structure of B using opt and frequency.

3-Create an input file which includes optimized structures of A and B where the closest atom in A is more than 4 Angstrom  from the closest atom in B.

4-Run minimization for a & B (in one input file) with opt (without frequency)

5-After achieving optimization, create an input file from the minimization output and run minimization with opt and frequency.

Rafik

Sir,

Thank yo so much for your clarification.

See also an interesting discussion from Tatiana Korona about the difference between interaction and binding energy and how to calculate them (including BSSE):

https://www.researchgate.net/post/What_is_the_simplest_way_to_calculate_Basis_Set_Superposition_Error_BSSE

If want to calculate the binding energy through Gaussian 09 of a molecule suppose that it is AB then-

1) Optimize the molecule AB with the the keyword opt+frequency for the minimum energy

2) Find out the minimum energy A and B separately using the same keyword as above.

3) Now subtract the energy as

{ AB - (A+B)}= Binding energy of AB

Thank you all for your valuable suggestions.

Dear Elvis,

To make sure that you have a ground state (GM) structure and not an imaginary or TS structures. For GM all frequencies should be positive.

Rafik

Dear Elvis

You can read this : J. Chem. Ed. 2007, vol.84, p. 1225

The steps to calculate a binding energy using Gaussain 09 is relatively straightforward in computational chemistry but the process itself can become extremely difficult depending on:

The types of molecules involved (size, complexity, etc.)

The desired accuracy of your final answer

The environment that the molecules reside in (gas phase, aqueous phase, etc.)

To determine the binding energy, you would use the following equation:

Ebind=Eopt-dimer−(Eopt-mon1+Eopt-mon2)

Good luck

Marius

Thanks for all answers. It will work for me, I mean I hope :D

what is the unit of binding energy?

calculation of binding energy by gaussian by the classic formula like below

1) Optimize the molecule AB with the the keyword opt+frequency for the minimum energy 2) Find out the minimum energy A and B separately using the same keyword as above. 3) Now subtract the energy as { AB - (A+B)}= Binding energy of AB

BUT THIS IS NOT GOOD I find binding energy for metal clusters of Ag,Pt and Pd around 500 ev instead of 2 to 4 eV and this is Grazzy, so what to do exactly???

Merci

- Optimize the molecule AB with the the keyword opt+frequency for the minimum energy

- Find out the minimum energy A and B separately using the same keyword as above.

- Now subtract the energy as

Binding energy of AB =AB - (A+B)

Dear Researchers

I read your answers for binding energy and I would like to add answer with different point of view. If the system consist of a certain molecule and you want to add an atom to this molecule (like the adhesion of polyethylene terephthalate on Aluminum), in this case the binding energy will find by:

Binding Energy=absolute value of the difference between (total electronic energy for relativity large separation distance between the atom and basic unit of PET(R>r0, usually larger than 4 angstrom depending on the system type) and the minimum energy of the system( this can be calculated by changing the distance from 1 to large R ).

About the unit of the binding energy, the calculated binding energy values will be in Hartree.

They can be converted to other units.

In gaussian16, they have automate the binding energy calculations, you just need to run single point calculation with counterpoise correction via defining the atom-pairs.

Note: Above step need to be done on the optimized complex.

Dear Karuppusamy Masiyappan

if ur focus is only complexation energy/binding energy, u can skip those. recommend answer if u found them helpful.

Hello everyone, I read everyone's answers and I have a question: can I use GAUSS to calculate the interaction energy between two molecules after docking?

Using the two keywords (opt, freq) and the formula of binding energy --> The energy of adsorption (or the energy of interaction). Have a good day!!!