Intermolecular binding strength

Intermolecular Binding Strength in Halogen-Bonded Complexes ... 

In reviewing the performance of density functional theory applied to hydrogen bonded complexes of moderate strength, we repeatedly noted a systematic underestimation of the interaction energies for many types of functionals, usually below 2 kcal/mol. This has been related by some researchers to the inability of modem functionals to describe those contributions to intermolecular binding energies which stem from dispersion forces. Dispersion... 

The HOH—NH3 complex served as a recent test for symmetry-adapted perturbation theory (SAFT). Basing their work on earlier formalism", which was further elaborated, Lan-glet et al. observed that a pure perturbation approach yielded an intermolecular separation that was somewhat too long, and underestimated the binding strength of the complex. Better correlation with experimental quantities, as well as with other acctirate computations, is obtained by a hybrid approach, wherein the dispersion energy, computed by SAPT, is added to the (counterpoise corrected) SCF portion of the interaction energy. This conclusion was found to apply not only to HOH—NH3, but also to the homodimers of HF, H O, andNH,. 

How to determine the angular geometry and strength of intermolecular binding for an isolated dimer... 

Groups that can be alkylated in this way include -SH, -OH, =NH, and -COOH however, not all irreversible antagonists act by forming a covalent bond. Some may fit the binding site so well that the combined strength of the other kinds of intermolecular interaction (ionic, hydrophobic, van der Waals, hydrogen bonds) that come into play approaches that of a covalent link. 

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