Ab initio calculation of the force field of the hydrogen fluoride dimer

Abstract

The potential energy surface of the hydrogen fluoride dimer is studied with ab initio LCAO-SCF theory. The geometry of the dimer is determined using minimal, split valence, and polarized basis sets. The results are somewhat dependent on basis set with the polarized basis giving the best agreement with the recently reported structure of the HF dimer from its radio frequency and microwave spectra. The split valence basis set is used to determine the nature of the potential surface corresponding to the tunnelling motion of the HF dimer. A barrier of 1.1 kcal/mole to this motion is calculated. The intermolecular and intramolecular vibrational frequencies of the complex are predicted from force constants calculated from the potential surface.