VIBRATION-TUNNELING ENERGY LEVELS OF $(HF)_{2}$ FROM CLOSE-COUPLING CALCULATIONS ON AN AB INITIO POTENTIAL SURFACE

Abstract

Author Institution: Department of Chemistry, Amherst College; Herzberg Institute of Astrophysics, National Research Council Canada; Institut F\""ur Theoretische Chemie und Strahlenchemie der Universit\""at, Wien, A-1090 Wien, W\""ahringerstrase 17, Austria.Using the analytical expression developed by Bunker, $et. al.^{1}$ for the ab initio potential enery surface of HF $dimer,^{2}$ close-coupling calculations are performed giving the energies of excited vibration and vibration-tunneling states. These results are compared with experiment when possible and with the results of approximate methods of calculation. The large number of channels required for convergence indicates that in some ways the HF dimer resembles a ``normal'' strongly-bound molecule more closely than a weakly-bound complex such as$(H_{2})_{2}.$ $^{1}$ P.R. Bunker, M. Kofranek, H. Lischka, and A. Karpfen, J. Chem. Phys. 89, 3002 (1988). $^{2}$M. Kofranek, H. Lischka, and A. Karpfen, Chem. Phys. 121, 137 (1988)