Correlation, effects hydrogenation energies

ST. D. Sokolov (Moscow) By which method was the dispersion term of the energy of the hydrogen bond calculated If it was calculated by London s formula then, first, it should be remembered that it is not applicable near the equilibrium state and, second, that in reality the dispersion interaction (the correlation effects) does not enter additively the energy of the electronic shell... 

Reuben J (1986) Intramolecular hydrogen bonding as reflected in the deuterium isotope effects on carbon-13 chemical shifts. Correlation with hydrogen bond energies. J Am Chem Soc 108 1735-1738... 

Calculations of a similar nature have demonstrated that replacement of both hydrogens of water, yielding dimethyl ether, also has only a minor effect upon the nature of the H-bond in the water dimer. With their polarized basis set, and with inclusion of corrections for BSSE, dispersion, and intramolecular correlation effects, these authors found the first methyl substitution raises the binding energy by 0.5 kcal/mol and the second by 0.6. The authors cautioned that an unpolarized basis set would fail to pick up these small effects, which they attribute to Coulomb and dispersion components of the interaction. 

Del Bene, J. E., Basis set and correlation effects on computed negative ion hydrogen bond energies of the dimers AH AH -1 AH =NH OH, and FH, International Journal of Quantum Chemistry, Quantum Biology Symposia 14, 27-35 (1987). 

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