Sharing of Electrons in Molecules: Characterization of Hydrogen Bonds

Abstract

The behaviors of the electrons in binary complexes formed from HF, H2O, and NH3 as well as in the complex formed between HF and CH4 are analyzed at the single electron level in order to characterize the nature of intermolecular bonding in dimers that may contain hydrogen bonds. The analysis uses the quantitative measures of the degree to which a single electron is shared between two points ζ and ζ‘, the sharing index I(ζ; ζ‘), and the underlying sharing amplitude 〈ζ; ζ‘〉, as well as the derived quantities, bond indices, self-sharing indices, delocalization indices, and volume−point sharing indices. The bond indices, together with the delocalization indices and the self-sharing indices, give a gross dissection of the sharing of an electron between the volumes associated with atoms and between molecules. These indices give a preliminary indication of the variety of the strengths of sharing in the complexes, but they do not necessarily distinguish between bonding and antibonding sharing. It is the sharing am...