Yes, the difference between the total energies of products and individual reactants will give you binding energy.

In the case of Graphene, since it has only C atom. The difference of total energy of Graphene and number of times of single C atom total energy, in simple as below

Binding Energy = Total energy of Graphene - (n x Total energy of C atom)

where n is the number of C atoms in the Graphene you have studied.

Ok, Mr Chittari is right.

You can calculated the total energy of unit cell structures of graphene by DFT, also the total energy of one isolated C aotm.  Now, use:

Binding Energy = Total energy of Graphene - (n x Total energy of C atom)

where n is number of C atoms in calculated unit cell (in hexagonal unit cell there are two carbon atoms).

Please notice that the input parameters in all calculations must be same.

binding energy=total energy of graphene unit cell - n*(energy of C atom) + BSSE correction , n: number of C atom in a unit cell

In The Name Of GOD

Dear Janani Kumar

I think two important subjects should be added to the descriptions of other friends. As first, you should divide their formula to the total number of carbon atoms. Second is about the size of super cell or cluster which you use for calculating the binding energy. By increasing the size of cluster, the binding energy decreases since size confinement decreases. Of course it will saturate to a value which is very near to the binding energy of infinite graphene sheet. If you use a suitable code such as VASP, SIESTA, or QUANTUM ESPERSSO, and consider unit cell (or super cell with suitable k-points) of graphene, since these codes solve the equations for crystal structures under period boundary condition, you can find the best results.

Best Regards

H.Simchi