SCF MO LCGO studies on hydrogen bonding: The hydrogen fluoride dimer

Different geometrical configurations of the hydrogen fluoride dimer have been studied by SCF LCGO MO calculations expanding the molecular wavefunctions into an extended basis set of gaussian type functions. For the minimum energy geometry a structure with a single linear hydrogen bond between the fluorine nuclei was obtained with an equilibrium FF distance of d(FF) = 2.85 angstrom (experimental FF distance in the cyclic hexamer 2.53 angstrom) and an HFH bond angle of beta = 140 degrees (experimental 140 degrees +/- 5 degrees). The binding energy was computed to be B = 4.50 kcal/mole (experimental 6.0 +/- 1.5 kcal/mole).