Ground-state stationary points on the potential energy surface of the reaction CF22++H2O-->OCF++HF+H+ were calculated using the density-functional theory hybrid method B3LYP and the ab initio coupled cluster singles and doubles with perturbative triples [CCSD(T)] algorithm. The calculations reveal a reaction mechanism involving two transition states. The first transition state involves the migration of one hydrogen within the primary collision complex and the second corresponds to the loss of a proton. The neutral HF molecular product is formed in its stable ground (1)Sigma state. Comparison of activation energies for the reactions of CF22+ with H2O and with D2O, calculated from Becke three parameter Lee-Yang-Parr (B3LYP) zero-point energies, slightly favor the H2O pathway by 0.04 and 0.07 eV for the first and second activations, respectively. Rate constant calculations using Rice-Ramsperger-Kassel-Marcus/quasiequilibrium theory also kinetically favor the H2O pathway in comparison with the D2O pathway. However, the magnitudes of the calculated rate constants are so large (10(12)-10(14) s(-1)) that the differences between the rates of reaction of CF22+ with H2O and with D2O should not be distinguished by a crossed-beam time-of-flight mass spectrometer experiment. Indeed, the ion yields reported in this paper from new collision experiments between CF22+ and D2O showed no isotope effect when compared with previous data from collisions of CF22+ with H2O. (C) 2003 American Institute of Physics.