|Quantum Chemistry Laboratory|
|Prof. N. Rösch|
De = 2 E(H) + E(O) - E(H2O)Give De also in kJ/mol. For unit conversion see the help section. The experimental value is : 971.6 kJ/mol. Compare to the calculated value !
E(A······B) = E(A) + E(B)Not every quantum chemical method exhibits the property that the accuracy of the resulting total energy is independent of the numbers of electrons of a molecular system. For example, the Configuration Interaction method with Single and Double substitutions (CISD) lacks size consistency. To calculate the binding energy of a molecue AB using CISD, the energy of the supermolecule A······B is also required, not just the total energies of the two sub-systems A and B.
Here, we leave aside the discussion under which circumstances density functional methods and related methods as the Becke3LYP hybrid method are size consistent. We calculated the binding energy in the straightforward fashion, as indicated above.
|||Calculated from data in: M. W. Chase, Jr., C. A. Davies, J. R. Downey, Jr., D. J. Frurip, R. A. McDonald, and A. N. Syverud, "JANAF Thermochemical Tables, Third Edition", J. Phys. Chem. Ref. Data, 14 (1985) Supplement No. 1, p. 1274.|
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