Abstract: | The geometries of the reactant, product, and transition state of the reaction between acetylene and the hydrogen atom have been optimized at the level of HF /6-31G using the energy gradient method. The barrier height for this reaction was calculated to be 105.9 kJ/mol with a zero-point energy correction and elimination of spin contamination. The intrinsic reaction coordinate (IRC ) for this reaction was traced and the coupling between the IRC and normal modes was analyzed along the IRC . The variational transition-state theory with the correction of the tunnel effect has been used to evaluate the reaction rate constant. It is in good agreement with an experimental estimate. © 1994 John Wiley & Sons, Inc. |