Quantum reaction dynamics of Cl+HCl -> HCl+Cl: vibrationally non-adiabaticreactions

Quantum reaction dynamics of Cl + HCl --> HCl + Cl for J (total angular mom entum)= 0 is studied with use of the hyperspherical elliptic coordinate app roach recently proposed by the authors. Thanks to the numerical efficiency of this approach, the reactions involving vibrational quantum jumps up to t hree are calculated accurately. Actually, all transitions among the states up to nu = 3 and j = 15, in other words up to the total energy E = 1.3 eV, are covered, where nu and j represent vibrational and rotational quantum nu mbers, respectively. Because of the symmetry of the system, the vibrational ly adiabatic reactions are generally more probable than the non-adiabatic o nes. However, some specific vibrationally non-adiabatic reactions even with two or three vibrational quantum jumps are found to occur efficiently. The concepts of potential ridge and non-adiabatic transitions at avoided cross ings near the ridge lines enable us to comprehend the reaction mechanisms n icely. (C) 1999 Elsevier Science B.V. All rights reserved.