Basically you will need to optimize the geometries of the molecule of interest and its radical without the cleaved H with the software of your choice, and also the computational method of your choice (if you don't know what to use, try to follow some "recipes" in previous works dealing with BDEs). In fact, it would be a good idea to check if you are able to repeat some of the calculations reported in the literature.

From the calculated energies of the molecule, its radical and of H (isolated atom) you should be able to calculate the BDE as:

Energy(radical)+energy(H)-energy(molecule)

You can use the exact energy for H if you want, i.e. -0.5 hartrees

Note that several papers report Bond dissociation enthalpies, not energies!, which means that energies are including thermal corrections for the temperature of interest (usually the standard temperature, i.e. 298.15 K). Go here for more details: http://www.gaussian.com/g_whitepap/thermo.htm

Calculations of this type can be done with a variety of quantum chemistry programs and program suites, including Gaussian, Q-Chem. NWChem, Spartan, Gamess, and many others. Which one you choose depends on your budget and expertise. Make sure to carefully research which quantum methods are reasonably reliable for BDE calculations. This reference may be helpful: http://onlinelibrary.wiley.com/doi/10.1002/cjoc.200590194/abstract

The calculation of BDE a molecule is not straightforward. No package will present these energies at end of the calculations. Each package will give total energy after calculation. One need to do the separate calculations for BDE.

Bond dissociation energy (BDE) is a measure of the bond strength in a chemical bond. It is defined as the standard enthalpy change when a bond is broken by a reaction, with reactants and products of the reaction. For instance, the bond-dissociation energy for one of the A-B bond in A2B2 is defined as follows:

A2B2-----> A2B + B

The BDE of A-B bond will be calculated as follows:

BDE(A-B) = [dH(A2B) + dH(B)] - dH(A2B2).

In order to estimate the dH values of each fragments in products and reactants, one has to optimize each fragment and find the enthalpy.

In any package, one has to do set of calculations to find BDE.

We did a lot of BDE calculations with high level theory for many small organic molecules:

Strain Energy of Small Ring Hydrocarbons. Influence of C−H Bond Dissociation Energies

Robert D. Bach and Olga Dmitrenko

J. Am. Chem. Soc., 2004, 126 (13), pp 4444–4452

Publication Date (Web): March 13, 2004 (Article)

DOI: 10.1021/ja036309a

Effect of Geminal Substitution on the Strain Energy of Dioxiranes. Origin of the Low Ring Strain of Dimethyldioxirane

Robert D. Bach and Olga Dmitrenko

J. Org. Chem., 2002, 67 (11), pp 3884–3896

Publication Date (Web): May 09, 2002 (Article)

DOI: 10.1021/jo025743c

The Effect of Substitutents on the Strain Energies of Small Ring Compounds

Robert D. Bach and Olga Dmitrenko

J. Org. Chem., 2002, 67 (8), pp 2588–2599

Publication Date (Web): March 19, 2002 (Article)

DOI: 10.1021/jo016241m

Dear Researcher, Thanks you so much for your valuable time and suggestions. I am looking for BDE calculations for Phenolic hydroxyl groups in our synthetic molecules to correlate with it's anti-oxidant activity.

Could anybody please suggest me about free/free for academic software which can be used for DBE calculation.

I am also going through the links provided by you all. I highly appreciate your suggestions. Thanks again.

Giri

University of Queensland.

If you look at the answers, you will already find a number of program named there.

A list of quantum chemistry programs with some properties and licences can be found here: http://en.wikipedia.org/wiki/List_of_quantum_chemistry_and_solid-state_physics_software

You will need some code with academic or open licence (like GPL or BSD) and most likely use DFT or post-HF methods employing GTOs. NWChem or Gamess are examples of such.

But as your question sounds to me as if you are new in the field: keep in mind that quantum chemistry calculations can not and should not be carried out without profound prior knowledge of what is being done in the calculations ("theory").

(Even) If you get your program to smoothly operate without any errors (which itsself is a task that will take some time), there are a lot of issues concerning the details of the calculations that heavily influence the reliability of your results and, maybe even more important, your interpretation of the results.

So, long story short: if you don't know what you do, you can use the best code but only produce a lot of meaningless numbers and heat which you certainly don't want.

If you don't have any experience in this field, either be prepared to spend a lot of time on gaining this experience or try to find an expert to collaborate with.

I think this link can help you:

http://www.sciencedirect.com/science/article/pii/S0166128099000470

Check this:

O-H BDE

Gomes JRB, Riberto da Silva MAV (2003) Gas-Phase Thermodynamic Properties of Dichlorophenols Determined from Density Functional Theory Calculations. J Phys Chem 107: 869–874. doi: 10.1021/jp026707k.

N-H BDE (very complete study)

Solvent and Structural Effects in the N-H Bond Homolytic Dissociation Energy J. R. B. Gomes, M. D. M. C. Ribeiro da Silva, M. A. V. Ribeiro da Silva J. Phys. Chem. A, 108 (2004) 2119. DOI: 10.1021/jp037996v

C-H, N-H, O-H BDE

Theoretical study on the stability of formylphenol and formylaniline compounds and corresponding radicals: O-H or N-H vs C-H bond dissociation. José R. B. Gomes J. Phys. Chem. A, 113 (2009) 1628. DOI: 10.1021/jp8101354

Dear Dr. José Gomes, Thanks for the references. Surely I will go through it. Giri

Basically you will need to optimize the geometries of the molecule of interest and its radical without the cleaved H with the software of your choice, and also the computational method of your choice (if you don't know what to use, try to follow some "recipes" in previous works dealing with BDEs). In fact, it would be a good idea to check if you are able to repeat some of the calculations reported in the literature.

From the calculated energies of the molecule, its radical and of H (isolated atom) you should be able to calculate the BDE as:

Energy(radical)+energy(H)-energy(molecule)

You can use the exact energy for H if you want, i.e. -0.5 hartrees

Note that several papers report Bond dissociation enthalpies, not energies!, which means that energies are including thermal corrections for the temperature of interest (usually the standard temperature, i.e. 298.15 K). Go here for more details: http://www.gaussian.com/g_whitepap/thermo.htm

Dear Dr. José Gomes, again thank you so much for your detailed explanation about BDE. Now, I have got basic idea about BDE. As I am a medicinal chemist working in synthetic chemistry and drug design. I am using drug design software (Maestro from Schrodinger, Sybyl-Tripos) since last couple of years but have no experience with quantum chemistry calculations. Recently, I have seen couple of research papers correlation antioxidant activity of Phenolic compounds with their -OH BDE. As our group also synthesized phenolic compounds with good antioxidant activity so, we want to correlate it with its -OH BDE.

I wish you good luck for the calculations. You are right there is (some) a correlation between antioxidant activity and BDEs.

How can I calculate the interaction strength between B-A-B and B-C-B bonds?

What is the input for calculated  BDE of OH radical ? Help me

for instance

# CBS-Q

title

0 2

coordinates

Dear Sir, or Madam,

I have a short question. ZPE value in results .out file is Hartree-Fock or Kcal/mol ?

you have to multiply it by 627.51 to get in kcal/mol

 Dear Olga Dmitrenko,

I have a short question. I want to take MOs image in .out flie; you can share keyword 

Thank you so much

Dear Nguyen,

You should use chk file for that and gaussview program. Read stuff here http://gaussian.com/g_prod/gv5b.htm  and don't think I remember everything, I always refer to manuals and internet search

Dear friends I have to calculate the BDE of some molecules, please suggest me the best possible level of theory and the functional.

There is no 'best', there is what you can afford and what you can not. If you can afford a CCSD(T) calculation and extrapolation to complete basis set, then you are probably within chemical accuracy.

In case you can not afford this extremely expensive and accurate level, standard density functional theory methodologies are, for example, B3LYP with the GD3BJ correction and a triple-Z basis set, or M062X with a triple Z basis set still (to minimize self-interaction errors). Still, you should take a look at the possible errors of density functional approximations, specially in high multiplicity open shell states that can result from bond breaking.

Be careful! Remember computational chemistry is a GIGO field: garbage in, garbage out!

There are many options available and the best one will likely depend on the size and character of the moleclues under investigation. The wikipedia page on quantum chemistry composite methods, such as the method suggested by Olga Dmitrenko above, is worth a look. These methods can provide relatively accurate energies without having to understand all the subtleties of all the computational chemistry methods used.

José R B Gomes Thanks for your answer, it was very enlightening, and the best answer in my opnion. Dr José, could you send some references that can support your statements? in the case the expression:

Energy(radical)+energy(H)-energy(molecule)

Renyer Costa: Please see my other comment. Some "useful" information can be found for instance in doi: 10.1021/jp026707k. Good luck!

José R B Gomes I sent to you a message in private! Thanks for the reference! Best regards

May using gaussian 09w software