title: Interpretation of intermolecular geometric isotope effect in hydrogen bonds: nuclear orbital plus molecular orbital study.
abstract: The intermolecular geometric isotope effect (GIE) in hydrogen bond A-X···B (X = H and D) is investigated theoretically using the nuclear orbital plus molecular orbital (NOMO) theory. To interpret the GIE in terms of physically meaningful energy components such as electrostatic and exchange-repulsion interactions, the reduced variational space self-consistent-field method is extended to the NOMO scheme. The intermolecular GIE is analyzed as a two-stage process: the intramolecular bond shrinkage and the intermolecular bond elongation. According to the isotopic shifts of energy components described by the NOMO/MP2 method, the intermolecular GIE is approximately interpreted as a process reducing the exchange-repulsion interaction after the decrease of electrostatic interaction.
authors.affiliation: Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University , Tokyo 169-8555, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ikabata
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Imamura
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakai
mesh_terms: D006860:Hydrogen Bonding; D007554:Isotopes / Q000737:chemistry; D008956:Models, Chemical; D015394:Molecular Structure; D055672:Static Electricity
chemical_list: D007554:Isotopes