How to calculate binding energy

[srinubarc]

Dear Members

I had optimized a model periodic structure which contains boron, carbon and lithium, how can i calculate binding energy or stabilization energy of the model system to state it as a stable one.

Thanks in advance

With regards
K Srinivasu

[admin]

you can calculate either the formation energy or the cohesive energy, depending on the assumed ground state of the atoms for
B,C and Li:
the general way to do it is to subtract the energies:
E(AmBn) - m*E(A) -n*E(B)
if the
-- energy ot the free atoms are used, you obtain the cohesive energy (please check whether Hund's rule is followed, this should be safely done for s,p atoms)
-- if the energy of the atom in the thermodynamic ground state phase of the respective element is used (Li bulk, B bulk, O molecule), you obtain the formation energy.
the compound formation is exothermic, if the difference is negative (ie if the E of the compound is more negative than the energies of its constituents).

please note that the calculations for the sub-systems have to be done on the same level of accuracy (energy cutoffs,..)