Journal of Molecular Structure (Theochem), 135 (1986) 357-368 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands THE HYDROGEN BONDING INFLUENCE ON POLARIZABILITY AND HYPERPOLARIZABILITY. A DERIVATIVE HARTREE-FOCK STUDY OF THE ELECTRICAL PROPERTIES OF HYDROGEN FLUORIDE AND THE HYDROGEN FLUORIDE DIMER” CLIFFORD E. DYKSTRA and SHI-YI LIU Department of Chemistry, University of Illinois, 505 S. Mathews Avenue, Urbana, IL 61801 (U.S.A.) DAVID J. MALIK Department of Chemistry, Indiana University -Purdue University at Indianapolis, Indianapolis, IN 46223 (U.S.A.) (Received 27 June 1985) ABSTRACT Derivative HartreeFock calculations have been carried out to explore the dependence of the molecular dipole polarizability and hyperpolarizability tensors of the HF dimer as a function of the intermolecular separation. The results show a diminishing axial hyper- polarizability (p) in the course of hydrogen bond formation. The polarizability (a) changes little. The changes in the hyperpolarizability can be well explained as arising from the hyperpolarizability induced by the field of one monomer via the second and third hyper- polarizability of the other. This is consistent with the important role of simple electrical interactions in hydrogen bonding and indicates that the electrical properties of the dimer can be well predicted from the electrical properties of the isolated monomers. INTRODUCTION One way of probing the interactions involved in hydrogen bonding is by examining the properties of a hydrogen bonded complex or cluster. Signifi- cant changes in the electronic structures of the constituent molecules may give rise to significant changes in the properties upon hydrogen bond forma- tion, and the nature of those changes is related to the hydrogen bonding that takes place. We have carried out calculations to examine the electrical properties of a particular hydrogen bonded system, the hdrogen fluoride dimer, which has been well-studied experimentally [l-lo] and theoretically [ll--251. A dipole moment surface already exists [24], and so the calcula- tions reported here concern the molecular dipole polarizabihty and hyper- polarizability. *Dedicated to Professor Robert S. Mulliken. 0166-1280/86/$03.50 0 1986 Elsevier Science Publishers B.V.