AB-INITIO POTENTIAL-ENERGY SURFACE AND VIBRATIONAL FREQUENCIES OF A ((1)A'') HCF

An extensive ab initio MRCI study of the (A) over tilde((1)A '') surfa ce of HCF is reported that includes characterization of the equilibriu m geometry and the barriers to dissociation and linearity. An analytic potential energy surface in the equilibrium region was fitted to the computed energies that allowed the variational calculation of the vibr ational fundamentals, overtones and combination bands to similar to 68 00 cm(-1). The computed bend progression is in good agreement with the experimentally observed progression. The spectroscopic constants of H CF in the ground (X) over tilde((1)A') and lowest excited (a) over bar ((3)A '') states were also computed using MRCI and coupled cluster tec hniques. (C) 1998 Published by Elsevier Science B.V. All rights reserv ed.