WEAK INTERACTIONS BETWEEN HYDRACIDS / BINARY ACIDS: SOME CONSIDERATIONS FROM A DFT ANALYSIS.

Non-covalent interactions involving element-hydrogen contacts are a central part in supramolecular chemistry and play essential roles in biomolecular structure. Reported here is a systematic computational analysis of such interactions within XH_n---YH_m dimers, where X and Y are C, Si, N, P, O, S, F and Cl, respectively. Two functionals are employed – the widely used BP86 and the M06-2X functional especially designed for describing noncovalent interactions. The interaction energies are found to be correlated with charge separation to a degree of 80%, suggesting that these noncovalent interactions can be reasonably explained/predicted by their electrostatic component. Energy decomposition analyses on the other hand suggest that correlation effects are the underlying root of the interaction. The rarely discussed intermolecular vibrations are also analyzed and noted to sometimes intercede in the typical observation windows for molecular spectroscopy. Moreover, in some cases notable effects of the non-covalent interactions are noted upon internal vibrations of the partners. [ABSTRACT FROM AUTHOR]