Quantum-mechanical calculation of the thermal rate constant for the H-2+Cl-> H+HClreaction

Accurate quantum calculations investigating the thermal rate constant and t he cumulative reaction probability of the H-2 + Cl --> H + HCl reaction on a new three-dimensional ab initio potential energy surface are presented. C omparing experimental and calculated results, the barrier height of the new surface is found to be too large by about 0.23 meV (0.53 kcal/mol). Almost perfect agreement with experiment is obtained for an improved potential en ergy surface obtained by slightly scaling the correlation energy so that th e dissociation energies of HCl and H-2 are reproduced accurately. Results o f accurate calculations and results obtained within the modified J-shifting approximation agree within a 10% error margin. (C) 1999 Elsevier Science B .V. All rights reserved.