On the electron-pair nature of the hydrogen bond in the framework of the atoms in molecules theory

• Published in: Chemical physics letters 2003-02, Vol.369 (1), p.248-255
• Main Authors: Poater, J., Fradera, X., Solà, M., Duran, M., Simon, S.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Density-functional theory; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(02)01928-0

Delocalization indices, as defined in the atoms in molecules theory, have been calculated between hydrogen-bonded atoms in 20 molecular complexes that are formed between several H-donor and acceptor molecules. In general, the delocalization index associated to an intermolecular hydrogen bond depends on the interaction energy of the complex, but also on the nature of the H-donor and acceptor atoms. The intermolecular delocalization index appears to be strongly correlated to the orbital interaction energy term as obtained from an energy decomposition scheme based on conceptual Kohn–Sham theory. Both the atoms in molecules theory and the energy decomposition analysis allow for a characterization of the hydrogen bonds in these complexes. In general, both kinds of analysis reveal that hydrogen bonding in these systems is not an essentially electrostatic interaction.