Knowledge Bank

Ab initio calculations at the Gaussian 70 SCF 4-31G level are used to construct a potential energy surface for $HF2-$ in the space corresponding to the bending and antisymmetric stretching displacements. A polynomial representation of the surface is used to calculate protonic, or vibrational, wave functions by expansion in a basis of harmonic oscillator product functions. The energies of these protonic states are compared to observed vibrational excitation energies. The quartic and biquadratic anharmonicities are shown to have particularly important effects on the energies of those protonic states corresponding to combinations of the bending and antisymmetric stretching vibrations.